If Odysseus goes to bed with Circe when she first asks, she will 'unman' him, that is, she will cut off his penis. Hermes tells Odysseus to first make Circe swear that she will do him no harm before he sleeps with her.
Circe is the witch-goddess that Odysseus and his crew meet after leaving the Cyclops Polyphemus's island. Odysseus sends a party of 23 men to search Aeaea (the name of the island and Circe's home). Circe invited them into her home and gave them food, but they all behaved like pigs, so that's exactly what Circe turns them into. Eurylochus, one of the men, does not eat, and he runs back to Odysseus to tell him. When Odysseus leaves, he meets Hermes, the messenger god who gives him a plant to protect him from the magic of Circe. being unable to defeat Odysseus, frees his men, but persuades Odysseus to stay with her. after the seasons pass though, Odysseus asks her to help him and his men go home. Circe tells him to seek out the blind prophet Teiresias in the land of the dead for a prophecy about his journey.
the underworld
tell them scylla is a bitchhhead
Book 12 of the Odyssey.
to tell calypso to release Odysseus
Zeus sends Hermes to Calypso to tell her to release Odysseus.
Not to kill them, which Odysseus warns his men not do to - and which they do anyway to their doom.
So that Circe could tell them the warnings of the sea, thus dodging the Sirens.
The land of the deads
with his son
the underworld