The story begins with the main protagonist of the last adventure, Darren Shan, and his guardian Larten Crepsley moving in for a drink of blood from an ex-scout. There is variety of sexual activities in the story. Darren is beginning to cope with life as a vampire's assistant though he still refuses to drink human blood and hates his companion, Mr. Crepsley, for turning him into a half vampire which has led him to faking his own death. Although he is far stronger than any human, and a shotput world champion, as he discovers, he is still finding it hard to adjust to his new life. His unchallenged strength causes him to be alone, as he can not make any human friends without breaking their hands. Larten teaches Darren all about vampirism and sometimes is shown regretting for blooding Darren and decides to take him to the Cirque du Freak.
He makes good friends with Evra Von, the snake boy. When they meet a young boy called Sam Grest who loves pickled onions, things begin to look up...and down. A local ecological preserver hippie known as Reggie Veggie (RV) befriends the trio of boys, but soon begins to learn about the animals that the freaks are feeding on - stolen from farmers. Reggie soon begins to worry Darren, so he goes to tell Mr. Tall but he becomes preoccupied on his way because Truska, the bearded lady, put together a new set of clothes for Darren. Darren must then do Evra's chores as he is tending to his sick snake, and forgets about telling Mr. Tall about Reggie that day.
A night of performance comes, as Mr. Tall finally gets wind of Reggie from Darren, but doubts that he can do any damage. But the Cirque did move along from that place, because of Reggie's threatening to call the police. Darren, who still refuses to drink human blood, decides not to perform and sets off. He hears a sound coming from the wolfman's cage, and decides to investigate. It was Reggie Veggie who was trying to free the wolf-man, but has no idea how violent the wolf man can be. After biting off Reggie's arms, the wolf-man sets off after a figure behind Darren, who has dropped a bag of clothes and onions which belong to Sam. Darren learns he was going to smuggle himself away with the circus. Eventually Sam is killed by the wolf man. While standing over Sam's corpse, Mr. Crepsley convinces Darren to drink Sam's blood, therefore "preserving" some of Sam's soul, including his love for pickled onions, as decided from a discussion of vampirism between Crepsley and Darren.