When schoolboy Alex Forbes is found holding the dead body of his schoolmate and friend Nigel Colby, forensic psychologist Sally Rowe is called in to determine whether or not Alex is fit to stand trial. Alex discloses some disturbing details to Sally, including Nigel's belief that both boys were descendants of the Knights Templar, his own belief that Nigel had a degree of mental control over Alex's own behaviour, and the boys' plans to kill a female schoolmate in the belief that it would allow them to gain supernatural powers. But as Sally, urged on by Alex's father, delves deeper into Nigel's family history, how many of these claims will turn out to be insanity and how many truth?