A head is found in the trunk of a car, & 2 drunk women are driving. Grissom & Catherine investigate.
Sara & Nick investigate a headless body found in the desert. At the autopsy Doc Robbins reveals that the body isn't human & Terri gets called in to identify what species the body belongs to.
Warrick looks into a murder in juvenile detention. His young friend James (from Crate & Burrial) is the only witness. If James testifies, he's dead. And if he doesn't he'll be spending most of his life in prison. Warrick tries to find enough evidence so that the DA won't need James' testimony.
Nick isn't too happy in this episode because Grissom still won't let him work solo on a case, when Warrick, who was promoted to CSI level 3 after Nick got to work solo a few times. Grissom tells Nick that he doesn't think he's ready yet & to prove his point gives him a simple riddle.
We also learn that Catherine just filed for divorce.
Grissom evaluates his team:
Catherine gets a "Keep up the good work"
Nick won't tell Sara what he got on his evaluation. Saying that it was private.
Grissom's evaluation for Sara: "Overall performance: Outstanding." "Ability
to prioritize:" ... "Improvement needed."
And finally Warrick was sitting in his evaluation as the episode ended.