The Son of Neptune

Before they left Camp Jupiter, Nico told Hazel he was going in search of the Doors of Death. He makes her promise to be careful even as they both worry that if she is successful at freeing Thanatos, it will mean her immediate return to the Underworld. On the boat, Hazel suffers terrible sea sickness, and her conversations with Frank and Percy cause her to fall into another blackout of memories.

Hazel and her mother now live in Alaska in a small, rented house. Her mother works as a maid, but at night she is possessed by the same woman who sent them to Alaska. The woman possessing Marie is Gaea and she is using Marie to force Hazel to help her raise her son, the giant Alcyoneus. Hazel escapes as often as she can and one day spends the whole day chasing a horse. When she arrives home late, she finds a note from Gaea ordering her to come to the island where the work is being done, in a cavern she calls the Heart of the Earth. On the way, a bird tells Hazel this will be the final night she will be required to come there. When Hazel arrives, her mother is in a trance over the pit, but she comes back to herself and apologizes to Hazel. She tells Hazel that Gaea will kill her but that she will allow Hazel to live. Marie encourages Hazel to leave. Gaea speaks, telling Hazel that she will wake after her son Alcyoneus wakes, and together they will oust the gods. Hazel knows she must stop Alcyoneus from waking. She uses her ability to push him back into the earth. As a result, she and her mother are crushed as the island collapses.