Boulton and Holmes investigate the latest in a long line of arson attacks. When forensic evidence places teen tearaway Adam Marrs at the scene of a previous fire, he is questioned and confesses to all of the recent attacks. However, a profiler brought in by Deakin to assist on the case isn't so sure that Marrs is responsible for the latest fire. Investigations reveal that the security guard on duty at the time was actually away from his post, moonlighting for another firm. When it is revealed that he abducted and tried to rape a young girl at the property, his evidence is discounted. Deakin's profiler seems to think that a serving fireman is responsible, but will her theory be proved right? Boulton isn't entirely convinced.