The entire CSI team investigates a disappearance at a local university. A young woman vanished, seemingly off the face of the earth.

A roller coaster runs off track leaving 6 people dead. The CSI team must uncover whether this was an accident, or foul play. Warrick and Catherine try to find the killer of a 13 year old girl.

Grissom is confronted with new evidence while on the stand of a murder trial of a restaurant owner. This development requires the reopening of the case and Eckley initiates an inquiry into Grissom and his team. The results of the inquiry lead to dramatic changes of the CSI team and the series.

The CSIs investigate a man's claim that his wife fell down a set of stairs in their home.