Grissom, Sara and Warrick are called in to investigate an abandoned, blood-splattered apartment and Nick and Catherine must examine a dead scuba diver lodged in a tree.

The team members are suspicious when the former tenant of the bloody apartment claims that his missing girlfriend is visiting her parents -- and the parents say she never showed up.

Meanwhile, Nick and Catherine are called to the site of a large fire and are confronted with the scuba diver found dead in the top of a tree near Lake Mead. Is it a murder or an urban legend turned fact?

Grissom and Nick investigate the death of a book restorer while Catherine and Sara are called to the scene of a fatal train crash. When the female book restorer is found dead and locked inside a "cage," a temperature-controlled workspace, Grissom and Nick attempt to determine whether this is a case of suicide or homicide. They discover that the key to solving the case may be a co-worker who suffers from autism. Meanwhile, Catherine and Sara are sent to comb through the wreckage of a collision between a train and an SUV and find out if it is a case of road rage or simply an accident.