Percy Jackson, son of Poseidon, God of the Sea, má veniec z veľmi hlbokého ospalého a pozerá sa na tvár s dvoma snake-haired ladies, ktoré refuse to die. Ale oni sa líšia z jeho problémov. Because Percy finds himself v tábore pre half-bloods, ktoré doesn't ring any bells for him. There's just one name he remembers from his pascu.