In the hall of Death, Odysseus made offerings and met Teresias who told him his prophecy and future. At the land of the dead, Odysseus saw friends he once knew and his mother.
Book XI: The Land of the Dead
The men went back to Circe's island, Aiaia, where Circe warned them about the Sirens, the path of Skylla and Kharybdis, the course of the Prowling Rocks, and Helios' cattle in Thrinakia.
Book XII: Sirens and the Two Paths
Dressed as Eumaios, Odysseus was unrecognizable. Athena then changed him back, revealing Odysseus in the presence of Telemachus. They planned to murder the suitors and no one knew of Odysseus' return except for his son.