When a roller coaster derails in an amusement park, there are six victims in the parking lot. Grissom, Nick, Sara and Capt. Brass investigate the case and soon they find that five deceased persons were in the train, but the employee Jim Nevins died twenty-hours before with a head trauma. Grissom interviews the park chief engineer Woody and learns that the old roller coaster has good maintenance. Grissom shows a nut to Woody and he says that it would be impossible to cause the train derail since there are eight sets that would have to lose. Meanwhile, Catherine and Warrick investigate the murder of the thirteen-year-old Tessa Press that was found murdered but not raped. Her mother Raina tells them that Tessa used to go to the house of a friend twice a week and she had assumed that her daughter was with her friend. Now they need to find what has happened to her.