Season synopsis
Contains spoilers for this season and earlier seasons.
The season opens where the previous one stopped: Grissom reaches Warrick after the shooting, and Warrick dies in his arms. The team mourns and investigates, finding that Undersheriff McKeen’s testimony does not fit the facts and that he used false evidence to frame dirty cop Daniel Pritchard, whom McKeen tries to drive to Mexico. After their car crashes, Nick finds McKeen wounded and resists his attempt to provoke a fatal shot. Brass arrests him. In later cases, new CSI Riley Adams joins the overworked team, while professor Raymond Langston first assists Grissom on a case involving serial killer Nate Haskell.
Grissom’s exit comes later, in episode ten, after he and Langston pursue Haskell and a copycat through an investigation shaped by the professor’s expertise. Grissom announces he is leaving and invites Langston to take a permanent place on the team; Langston’s first day as a CSI follows in episode eleven. Catherine leads the night shift through cases including a shooting in Koreatown where witnesses refuse to talk, a murder linked to a long-ago crime and a motel where Nick connects three killings across a year. Grissom’s departure leaves Catherine responsible for guiding an experienced team that must also teach its newest investigator.
Later cases bring Langston into danger when he and Riley are taken hostage after a gang shootout, and his academic past returns when a former graduate student is murdered. Catherine revisits an old case after a prisoner challenges its evidence, while a mysterious illness eventually links several deaths to a tattoo parlor. In the finale, the team investigates murders connected to a scam involving valuable poker chips, and Langston uses deadly force for the first time.