Young Darren Shan has been fascinated by spiders from an early age. His best friend, Steve "Leopard" Leonard has grown up reading horror comics and stories of the Wolfman and vampires.

One day, their other friend Alan comes across a flyer advertising the "Cirque Du Freak" and eagerly shows it to Darren, Steve, and Tommy. All the boys wanted to go. Each flyer could only get two tickets, however, so they play a game of chance to see who will go with Steve, which Darren wins.

Darren and Steve are mesmerized by the fantastic and disturbing show, especially by the act of the mysterious Mr. Crepsley and his giant spider Madam Octa. After witnessing a confrontation between Steve and Mr. Crepsley after the show in which Steve declares the latter to be a vampire, Darren sets his sight on Madam Octa, planning to steal her and use his knowledge of Mr. Crepsley's true nature to his full advantage.