A.  Tantalus, Pelops: the cannibalistic banquet
The Phrygian king Tantalus was allowed to socialize with the gods, but abused his privilege.  As a consequence he was punished: in the Odyssey  he stands in a pool of water up to his chin, but when he attempts to drink the water disappears into the ground; when he reaches up for the branches of fruit overhead, a breeze blows them beyond his grasp.  According to one story, his transgression was a terrible cannibalistic banquet: he  slew his son Pelops, cut him to pieces and set him as food before the gods.  Only Demeter ate one shoulder.  By the command of Zeus, Hermes replaced the pieces and Demeter replaced the missing shoulder by one made of ivory.

B. Pelops, Oenomaeus, Hippodamia, and the curse of Myrtilus
When Pelops grew to manhood, he went to Pisa and wooed Hippodamia, daughter of a king who compelled her suitors to run a race with him; they all lost, and he killed them.  But Pelops won by the treachery of a charioteer who took out the linchpin in the man's chariot.  When he claimed as a reward either half of the kingdom, or a first night with Hippodamia, Pelops threw him down a cliff.  He cursed the house of Pelops as he fell to the sea.  Pelops extended his power so much that the peninsula was called "island of Pelops" (Peloponnesos).

C. The children of Pelops:

1. The quarrel between Atreus and Thyestes
Atreus and Thyestes murdered their step-brother Chrysippus.  To escape the wrath of their father, they took refuge with their brother in law Sthenelus, king of Mycenae.  His son was killed by the descendants of Herakles, and so Atreus kept possession of the kingdom of Mycenae, which had been given him in charge by Eurystheus, and maintained it in virtue of possessing a golden lamb, which had been given him by Hermes for the purpose of exciting discord in the house of Pelops and avenging the death of his son Myrtilus (the charioteer whom Pelops had murdered).  Thyestes seduced his brother's wife Aerope, and with her aid got possession of the golden lamb and the kingdom.  As a sign that right and wrong had been confounded, Zeus turned the sun and the moon back in their curse.  Atreus recovered his kingdom and expelled Thyestes.

2. Thyestes' cannibalistic banquet
After Thyestes sent someone to murder him, Atreus invited Thyestes and his family from exile, and served up to him at table the limbs of his own sons.  Thyestes fled, and the land was afflicted with barrenness and famine.  Other atrocious acts follow in some versions; finally Thyestes and his son Aegisthus (a son he had by his daughter Pelopia) kill Atreus, seize the government of Mycenae, and drive Agamemnon and Menelaos out of the country.

D. The grandchildren of Pelops: story of the house of the sons of Atreus

    See Mycenean myths: chart 1

After the death of Atreus, Agamemnon and Menelaos go to Sparta, where the king gives them his two daughters in marriage, Clytemnestra to Agamemnon, and Helen to Menelaos.  Agamemnon then drives his uncle out of Mycenae and extends his dominions so that in the war against Troy the chief command is entrusted to him as the mightiest prince in Greece.

1. Aegisthus and Clytemnestra
2. Return and murder of Agamemnon by Clytemnestra with the complicity of Aegisthus

E. Retributive justice, civic justice: Orestes kills Clytemnestra and her lover, Aegisthus.  In most versions Electra urges him to exact the revenge.  In Aeschylus Orestes is pursued by the Furies (vengeful spirits of the dead), led by the ghost of his mother.

Images:
#1     Rape of Cassandra during the sack of Troy?
#2    Orestes avenges the murder of Agamemnon by stabbing Aegisthus in the  chest with a sword. Clytemnaestra raises an axe against Orestes, but Talthybius prevents her from acting.
#3     A young nurse stands, one hand raised in despair,between Orestes and Clytemnaestra, holding Penthilus, Orestes's son.
#4        Orestes kills Aegisthus
#5        Orestes pursued by the Furies
#7       Orestes, Aegisthus, Chrysothemis (Sister of Orestes and Electra)
 

See Mycenean myths:  chart 2
 

2. Orestes is commanded by Apollo to proceed to Athens, where a tribunal of the people, presided by the goddess Athena, acquits him.  This is a myth that supports the authority of the court of justice on the Areopagus, and consequently of the entire system of justice in Athens.