Zak, Nick and Aaron head to Ione, Calif., for an adventure in a condemned building known as Preston Castle. The castle has a dark history as a former reformatory that housed angry juvenile offenders and abandoned children.

It is the sight of an unsolved murder, countless instances of corporal punishment, and the scene of many tragic deaths due to ravaging epidemics of tuberculosis and yellow fever. The boys have their hands full in this episode with the aggressive ghosts that are trapped within the confines of Preston Castle.