Devin Drake, a twelve-year-old paranormal ghost detective, is asked by Cassie Waite, the smartest, most athletic girl at their middle school, to help with a ghost problem.It seems her family's house, built on the site of a former amusement park, is haunted by two roller coaster-riding ghosts from a century ago.While trying to figure out who they are and what they want, Devin realizes the amusement park spirits are in danger and he'll need all his paranormal powers to find them a new hangout in the afterlife.But when the ghosts trick Cassie into getting on the haunted coaster, Devin enlists the help of an offbeat, local historian to rescue Cassie from their world before she is trapped in it forever.