Note:

The screenwriters FAQ (the FAQ list for the SCRNWRIT email discussion list) lives at http://www.panam.edu/scrnwrit/. Section XIV (Writing Tips), Part D (Major League Tools), Item 7 contains the following:

THE THIRTY-SEVEN DRAMATIC SITUATIONS
By Georges Polti

1.  SUPPLICATION (To humbly petition).
Elements:  A persecutor, a humble petitioner, and a
           power in authority whose decision is doubtful.
A1   Fugitives imploring the powerful for help
     against their enemies.
A2   Assistance implored for the performance of a
     pious duty which has been forbidden.
A3   Appeals for refuge in which to die.
B1   Hospitality besought by the shipwrecked.
B2   Charity entreated by those cast off by their
     own people, whom they have disgraced.
B3   Expiration: the seeking of pardon, healing or
     deliverance.
B4   The surrender of a corpse, or relic, solicited.
C1   Supplication of the powerful for those dear to
     the suppliant.
C2   Supplication to a relative in behalf of
     another relative.
C3   Supplication to a mother's lover, in her
     behalf.

2.  DELIVERANCE.
Elements:  An unfortunate, a threatener, a rescuer.
A   Appearance of a rescuer to the condemned.
B1  A parent replaced on the throne by his
    children.
B2  Rescue by friends, or by strangers grateful
    for benefits or hospitality.

3.  CRIME PUNISHED BY VENGEANCE.
Elements:  An avenger and a criminal.
A1  The avenging of a slain parent or ancestor.
A2  The avenging of a slain child or descendant.
A3  Vengeance for a child dishonored.
A4  The avenging of a slain wife or husband.
A5  Vengeance for the dishonor, or the attempted
    dishonoring, of a wife.
A6  Vengeance for a mistress slain.
A7  Vengeance for a slain or injured friend.
A8  Vengeance for a sister seduced.
B1  Vengeance for intentional injury or
    spoilation.
B2  Vengeance for having been despoiled during
    absence.
B3  Revenge for an attempted slaying.
B4  Revenge for a false accusation.
B5  Vengeance for violation.
B6  Vengeance for having been robbed of one's own.
B7  Revenge upon a whole sex for a deception by
    one.
C   Professional pursuit of criminals.

4.   VENGEANCE TAKEN FOR KINDRED UPON KINDRED.
Elements:  Avenging kinsman, guilty kinsman, remembrance
           of the victim, a relative of both.
A1   A father's death avenged upon a mother.
A2   A mother avenged upon a father.
B    A brother's death avenged upon a son.
C    A father's death avenged upon a husband.
D    A husband's death avenged upon a father.

5.   PURSUIT.
Elements:  Punishment and fugitive.
A    Fugitives from justice pursued for crimes,
     political offenses, etc.
B    Pursued for a fault of love.
C    A hero struggling against a power.
D    A pseudo-madman struggling against an
     alienist.

6.   DISASTER.
Elements:  A vanquished power, a victorious
           enemy or a messenger
A1  Defeat suffered.
A2  A fatherland destroyed.
A3  The fall of humanity.
A4  A natural catastrophe.
B   A monarch overthrown.
C1  Ingratitude suffered.
C2  The suffering of unjust punishment or enmity.
C3  An outrage suffered.
D1  Abandonment by a lover or a husband.
D2  Children lost by their parents.

7.  FALLING PREY TO CRUELTY OR MISFORTUNE.
Elements:  An unfortunate; a master or a misfortune.
A   The innocent made the victim of ambitious
    intrigue.
B   The innocent despoiled by those who should
    protect.
C1  The powerful dispossessed and wretched.
C2  A favorite or an intimate finds himself
    forgotten.
D   The unfortunate robbed of their only hope.

8.  REVOLT.
Elements:  Tyrant and conspirator.
A1  A conspiracy chiefly of one individual.
A2  A conspiracy of several.
B1  Revolt of one individual, who influences and
    involves others.
B2  A revolt of many.

9.  DARING ENTERPRISE.
Elements:  A bold leader, an object, an adversary.
A   Preparations for war.
B1  War.
B2  Combat.
C1  Carrying off a desired person or object.
C2  Recapture of a desired object.
D1  Adventurous expeditions.
D2  Adventure undertaken for the purpose of
    obtaining a beloved woman.

10.  ABDUCTION.
Elements:  The abductor, the abducted, the guardian.
A   Abduction of an unwilling woman.
B   Abduction of a consenting woman.
C1  Recapture of the woman without the slaying of
    the abductor.
C2  The same case, with the slaying of the
    ravisher.
D1  Rescue of a captive friend.
D2  Of a child.
D3  Of a soul in captivity to error.

11.  THE ENIGMA.
Elements:  Interrogator, seeker, and problem.
A   Search for a person who must be found on pain
    of death.
B1  A riddle to be solved on pain of death.
B2  The same case, in which the riddle is proposed
    by the coveted woman.
C1  Temptations suffered with the object of
    discovering his name.
C2  Temptations offered with the object of
    ascertaining the sex.
C3  Tests for the purpose of ascertaining the
    mental condition.

12.  OBTAINING.
Elements:  A solicitor and an adversary who is
           refusing, or an arbitrator opposing parties.
A    Efforts to obtain an object by ruse or force.
B    Endeavor by means of persuasive eloquence
     along.
C    Eloquence with an arbitrator.

13.  ENMITY OF KINSMEN.
Elements:  A malevolent kinsman, a hated or
           reciprocally hating kinsman.
A   Hatred of brothers:
A1  One brother hated by several.
A2  Reciprocal hatred.
A3  Hatred between relatives for reasons of
    self-interest.
B   Hatred of father and son:
B1  Of the son for the father.
B2  Mutual hatred.
B3  Hatred of daughter for father.
C   Hatred of grandfather for grandson.
D   Hatred of father-in-law for son-in-law.
E   Hatred of mother-in-law for son-in-law.
F   Infanticide.

14.   RIVALRY OF KINSMEN.
Elements:  The preferred kinsman, the rejected
           kinsman, and the object.
A1  Malicious rivalry of a brother.
A2  Malicious rivalry of two brothers.
A3  Rivalry of two brothers, with adultery on the
    part of one.
A4  Rivalry of sisters.
B1  Rivalry of father and son, for an unmarried
    woman.
B2  Rivalry of father and son, for a married
    woman.
B3  Case similar to the two foregoing, but in
    which the object is already the  wife of
    the father.
B4  Rivalry of mother and daughter.
C   Rivalry of cousins.
D   Rivalry of friends.

15.  MURDEROUS ADULTERY.
Elements:  Two adulterers, betrayed husband or wife.
A1  The slaying of a husband by or for a paramour.
A2  The slaying of a trusting lover.
B   Slaying of a wife for a paramour, and in
    self-interest.

16.  MADNESS.
Elements:  Madman and victim.
A1  Kinsman slain in madness.
A2  A lover slain in madness.
A3  Slaying or injuring of a person not hated.
B   Disgrace brought upon oneself through madness.
C   Loss of loved ones brought about by madness.
D   Madness brought on by fear of hereditary
    insanity.

17.  FATAL IMPRUDENCE.
Elements:  The imprudent, the victim or the object lost.
A1  Imprudence the cause of one's own misfortune.
A2  Imprudence the cause of one's own dishonor.
B1  Curiosity the cause of one's own misfortune.
B2  Loss of the possession of a loved one, through
    curiosity.
C1  Curiosity the cause of death or misfortune to
    others.
C2  Imprudence the cause of a relative's death.
C3  Imprudence the cause of a lover's death.
C4  Credulity the cause of kinsman's death.

18.  OEDIPAL.
Elements:  The lover, the loved, and the revealer.
A1   Discovery that one has married one's mother.
A2   Discovery that one has had one's sister as
     mistress.
B1   Discovery that one has married one's sister.
B2   The same case, in which the crime has been
     villainously planned by a third person.
B3   Being upon the point of taking one's sister,
     unknowingly, as a mistress.
C    Being upon the point of violating,
     unknowingly, a daughter.
D1   Being upon the point of committing an
     adultery, unknowingly.
D2   Adultery committed unknowingly.

19.  SLAYING OF A KINSMAN UNRECOGNIZED.
Elements:  The slayer, the unrecognized victim.
A1   Being upon the point of slaying a daughter
     unknowingly, by command of a divinity or an
     oracle.
A2   Through political necessity.
A3   Through a rivalry in love.
A4   Through hatred of the lover of the
     unrecognized daughter.
B1   Being upon the point of killing a son
     unknowingly.
B2   The same as case B1, strengthened by
     Machiavellian instigation.
B3   The same as case (B2), intermixed with hatred
     of kinsmen.
C    Being upon the point of killing one's brother
     unknowingly:
C1   Brothers slaying in anger.
C2   A sister slaying through professional duty.
D    Slaying of a mother unrecognized.
E1   A father slain unknowingly through
     Machiavellian advice.
E2   The simple slaying of a father unrecognized.
E3   The same case reduced from murder to simple
     insult.
F1   A grandfather slain unknowingly, in vengeance
     and through instigation.
F2   Slain involuntarily.
F3   A father-in-law killed involuntarily.
G1   Involuntary killing of a loved woman.
G2   Upon the point of killing a lover
     unrecognized.
G3   Failure to rescue an unrecognized son.

20.  SELF-SACRIFICING FOR AN IDEAL.
Elements:  The hero, the ideal, the creditor or
           the person or things sacrificed.
A1   Sacrifice of life for the sake of one's word.
A2   Life sacrificed for the success of one's
     people.
A3   Life sacrificed for the happiness of one's
     people.
A4   Life sacrificed in filial piety.
A5   Life sacrificed for the sake of one's faith.
B1   Both love and life sacrificed for the sake of
     a cause.
B2   Love sacrificed to interests of state.
C    Sacrifice of well-being to duty.
D    The ideal of honor sacrificed to the ideal of
     faith.

21.  SELF-SACRIFICE FOR KINDRED.
Elements:  The hero, the kinsman, the creditor
           or the person or thing sacrificed.
A1   Life sacrificed for that of a relative or
     loved one.
A2   Life sacrificed for the happiness of a
     relative or loved one.
B1   Ambition sacrificed for the happiness of a
     parent.
B2   Ambition sacrificed for the life of a parent.
C1   Love sacrificed for the sake of a parent's
     life.
C2   For the happiness of one's child.
C3   For the happiness of a loved one.
C4   The same as 2, but caused by unjust laws.
D1   Life and honor sacrificed for the life of a
     parent or loved one.
D2   Modesty sacrificed for the life of a relative
     or a loved one.

22.  ALL SACRIFICED FOR A PASSION.
Elements:  The lover, the object of the fatal passion,
           and the person or thing sacrificed.
A1   Religious vows of chastity broken for passion.
A2   A vow of purity broken.
A3   Respect for a priest destroyed.
A4   Power ruined by a passion.
A5   Ruin of mind, health, and life.
A6   Passion gratified at the price of life.
A7   Ruin of fortunes, lives, and honor.
B    Temptations (see 12) destroying the sense of
     duty, pity, etc.
C1   Destruction of honor, fortune, and life by
      erotic vice.
C2   The same effect produced by any other vice.

23.  NECESSITY OF SACRIFICING LOVED ONES.
Elements:  The hero, the beloved victim, and
           the necessity for the sacrifice.
A1   Necessity for sacrificing a daughter in the
     public interest.
A2   Duty of sacrificing her in fulfillment of a
     vow to God.
B1   Duty of sacrificing, under the same
     circumstances, one's father.
B3   Duty of sacrificing, under the same
     circumstances, one's husband.
B4   Duty of sacrificing a son-in-law for the
     public good.
B5   Same case under the sake of reputation.
B6   Duty of contending with a brother-in-law for
     the public good.
B7   Duty of contending with a friend.

24.  RIVALRY OF SUPERIOR AND INFERIOR.
Elements:  The superior rival, the inferior
           rival, and the object.
A    Masculine rivalries.
A1   Of a mortal and immortal.
A2   Of two divinities of unequal power.
A3   Of a magician and an ordinary man.
A4   Of conqueror and conquered.
A5   Of victor and vanquished.
A6   Of a master and a banished man.
A7   Of usurper and subject.
A8   Of Suzerian King and Vassal Kings.
A9   Of a powerful person and upstart.
A10  Of rich and poor.
A11  Of an honored man and a suspected one.
A12  Rivalry of two who are almost equal.
A13  Rivalry of equals, one of whom in the past has
     been proved guilty of adultery.
A14  Of a man who is loved and one who has not the
     right to love.
A15  Of the two (or more) successive husbands of a
     divorcee.
B    Feminine rivalries.
B1   Of a sorceress and an ordinary woman.
B2   Of victor and prisoner.
B3   Of a queen and slave.
B4   Of lady and servant.
B5   Of a lady and a woman of humbler position.
B6   Of a lady and two women of humbler class.
B7   Rivalry of two who are almost equals,
     complicated by the abandonment of one.
B8   Rivalry between the memory or an ideal (that
     of a superior woman) and a vassal of her own.
B9   Rivalry of mortal and immortal.
C    Double rivalry (A loves B, who loves C, who
     loves D).
D    Oriental rivalries (Hindu polygamy).
D1   Rivalry of two immortals.
D2   Of two mortals.
D3   Of two lawful wives.

25.  ADULTERY.
Elements:  A deceived husband or wife and two adulterers.
A    A mistress betrayed:
A1   For a young woman.
A2   For a young wife.
A3   For a girl.
B    A wife betrayed:
B1   For a slave, who does not love in return.
B2   For debauchery.
B3   For a married woman.
B4   With the intention of bigamy.
B5   For a young girl, who does not love in return.
B6   A wife envied by a young girl who is in love
     with her husband.
B7   By a courtesan.
B8   Rivalry between a lawful wife who is
     antipathetic and a mistress who is congenial.
B9   Between a generous wife and an impassioned
     girl.
C1   An antagonistic husband sacrificed for a
     congenial lover.
C2   A husband, believed to be lost, forgotten for
     a rival.
C3   A commonplace husband sacrificed for a
     sympathetic lover.
C4   A good husband betrayed for an inferior rival.
C5   For a grotesque rival.
C6   For an odious rival.
C7   For a commonplace rival, by a perverse wife.
C8   For a less handsome, but useful rival (with
     comic false suspicions).
D1   Vengeance of a deceived husband.
D2   Jealousy sacrificed out of pity.
E    A husband persecuted by a rejected rival.

26.  CRIMES OF LOVE.
Elements:  The lover and the betrayed.
A1   A mother in love with her son.
A2   A daughter in love with her father.
A3   Violation of a daughter by her father.
B1   A woman enamored of her stepson.
B2   A woman and her stepson enamored of each
     other.
B3   A woman being the mistress, at the same time,
     of a father and son, both of whom accept the
     situation.
C1   A man becomes the lover of his sister-in-law.
C2   The man alone becomes enamored.
C3   A brother and sister in love with each other.
D1   A man enamored of another man, who yields.
D2   A woman enamored of a bull.

27.  DISCOVERY OF THE DISHONOR OF A LOVED ONE.
Elements:  The discoverer and the guilty one.
A1   Discovery of a mother's shame.
A2   Discovery of a father's shame.
A3   Discovery of a daughter's dishonor.
B1   Discovery that one's wife has been violated
     before marriage ... since the marriage.
B2   That she previously committed a fault.
B3   Discovery that one's wife has formerly been a
     prostitute.
B4   Discovery of dishonor on the part of a lover.
B5   Discovery that one's mistress, formerly a
     prostitute, has returned to her old life.
B6   Discovery that one's lover is a scoundrel, or
     that one's mistress is a woman of bad
     character ... the same discovery concerning a
     so-called king.
B7   The same discovery concerning one's wife.
C    Discovery that one's son is an assassin.
D1   Duty of punishing a son who is a traitor to
     country.  A brother who is a traitor to his
     party.
D2   Duty of punishing a son condemned under a law
     which the father has made.
D3   Duty of punishing a son believed to be guilty.
D4   Duty of sacrificing, to fulfill a vow of
     tyrannicide, a father until then unknown.
D5   Duty of punishing a brother who is an
     assassin.
D6   Duty of punishing one's mother to avenge one's
     father.

28.  OBSTACLES TO LOVE.
Elements:  Two lovers and an obstacle.
A1   Marriage prevented by inequality of rank.
A2   Inequality of fortune an impediment to
     marriage.
B    Marriage prevented by enemies and contingent
     obstacles.
C1   Marriage forbidden on account of the young
     woman's previous betrothal to another.
C2   The same case, complicated by an imaginary
     marriage of the beloved object.
D1   A free union impeded by the opposition of
     relatives.
D2   Family affection disturbed by the
     parents-in-law.
E    By the incompatibility of temper of the
     lovers.
F    Love.

29.  AN ENEMY LOVED.
Elements:  The beloved enemy, the lover, and the hater.
A    The loved one hated by the kinsman of the
     lover.
A1   The lover pursued by the brothers of his
     beloved.
A2   The lover hated by the family of his beloved.
A3   The lover is the son of a man hated by the
     kinsmen of his beloved.
A4   The beloved is an enemy of the party of the
     woman who loves him.
B1   The lover is the slayer of the father of his
     beloved.
B2   The beloved is the slayer of the father of the
     beloved.
B3   The beloved is the slayer of the brother of
     her lover.
B4   The beloved is the slayer of the husband of
     the woman who loves him, but who has
     previously sworn to avenge that husband.
B5   The same case, except that a lover, instead of
     a husband, has been slain.
B6   The beloved is the slayer of a kinsman of the
     woman who loves him.
B7   The beloved is the daughter of the slayer of
     her lover's father.

30.  AMBITION.
Elements:  An ambitious person, a thing coveted,
           and an adversary.
A1   Ambition watched and guarded against by a
     kinsman or patriot friend or by a brother.
A2   By a relative or person under obligation.
A3   By partisans.
B    Rebellious ambition (akin to #8).
C1   Ambition and covetousness heaping crime upon
     crime.
C2   Parricidal ambition.

31.  CONFLICT WITH A GOD.
Elements:  A mortal and an immortal.
A1   Struggle against a deity.
A2   Strife with the believers in a god.
B1   Controversy with a deity.
B2   Punishment for contempt of a god.
B3   Punishment for pride before a god.
B4   Presumptuous rivalry with a god.
B5   Imprudent rivalry with a deity.

32.  MISTAKEN JEALOUSY.
Elements:  The jealous one, the object of whose
           possession he is jealous, the supposed
           accomplice, and the cause or the author
           of the mistake.
A1   The mistake originates in the suspicious mind
     of the jealous one.
A2   Mistaken jealousy aroused by a fatal chance.
A3   Mistaken jealousy of a love which is purely
     platonic.
A4   Baseless jealousy aroused by malicious rumors.
B1   Jealousy suggested by a traitor who is moved
     by hatred.
B2   The same case, in which the traitor is moved
     by self-interest.
B3   The same case, in which the traitor is moved
     by jealousy and self-interest.
C1   Reciprocal jealousy suggested to husband and
     wife by a rival.
C2   Jealousy suggested to the husband by a woman
     who is in love with him.
C3   Jealousy suggested to the wife by a second
     rival.
C4   Jealousy suggested to a happy lover by a
     deceived husband.

33.  ERRONEOUS JUDGEMENT.
Elements:  The mistaken one, the victim of
           the mistake, the cause or author of
           the mistake, and the guilty person.
A1   False suspicion where faith is necessary.
A2   False suspicion (in which the jealousy is not
     without reason) of a mistress.
A3   False suspicions aroused by a misunderstood
     attitude of a loved one.
A4   By indifference.
B1   False suspicions drawn upon oneself to save a
     friend.
B2   They fall upon the innocent husband of the
     guilty one.
B3   The same case as B2, but in which the innocent
     had a guilty intention or in which the
     innocent believes himself guilty.
B4   A witness to a crime, in the interest of a
     loved one, lets accusation fall upon the
     innocent.
C1   The accusation is allowed to fall upon an
     enemy.
C2   The error is provoked by an enemy.
C3   The mistake is directed against the victim by
     her brother.
D1   False suspicion thrown by the real culprit
     upon one of his enemies.
D2   Thrown by the real culprit upon the second
     victim against whom he has plotted from the
     beginning.
D3   False suspicion thrown upon a rival.
D4   Thrown upon one innocent, because he has
     refused to be an accomplice.
D5   Thrown by a deserted mistress upon a lover who
     left her because he would not deceive her
     husband.
D6   Struggle to rehabilitate oneself and to avenge
     a judicial error purposely caused.

34.  REMORSE.
Elements:  The culprit, the victim or the sin,
           and the interrogator.
A1   Remorse for an unknown crime.
A2   Remorse for parricide.
A3   Remorse for an assassination... for a judicial
     murder.
A4   Remorse for the murder of husband or wife.
B1   Remorse for a fault of love.
B2   Remorse for adultery.

35.  RECOVERY OF A LOST ONE.
Elements:  The seeker and the one found.

36.  LOSS OF LOVED ONES.
Elements:  A kinsman slain, a kinsman
           spectator, and an executioner.
A1   Witnessing the slaying of kinsmen, while
     powerless to prevent it.
A2   Helping to bring misfortune upon one's people
     through professional secrecy.
B    Divining the death of a loved one.
C    Learning of the death of a kinsman or ally.
D    Relapse in primitive baseness, through despair
     on learning of the death of a loved one.

37.  MISTAKEN IDENTITY.
A    Thinking someone is rich when he's poor.
B    The wrong man caught in the web of fear.
C    Schizophrenia.