Percy Jackson is on a hill overlooking San Francisco Bay. Two gorgons—snake-headed monsters—are chasing him. He has already killed them multiple times over the past three days, but they will not stay dead. They cannot hurt Percy either, something they blame on the mark of Achilles they claim he has. The gorgons say that Percy killed their sister, Medusa and that the earth god, Gaea, brought them back from the dead to exact their revenge. Percy does not remember killing Medusa. Percy cannot remember much of anything beyond the past few months except for dim memories of Annabeth, a girl he believes to be his girlfriend. Lupa, the leader of a pack of wolves with whom he has lived and trained these past months, tells him that he will regain his memory if he completes the journey he is now on. Percy does not know what this journey will entail. His main concern is getting away from the gorgons, so he uses a serving platter one of the gorgons was carrying to slide down the hill.