The tenth anniversary of 9/11 proves a wrenching but clarifying passage for Mac, who suffered a terrible loss on that day. Meanwhile, an open-and-shut robbery/homicide proves more complicated than anyone had anticipated.

When an awkward teen is found dead, the team discovers that his efforts to win a sexy punk rock chick's heart may have gone a step too far.

When the body of a beautiful young woman is found in a stolen Ferrari, the investigation leads to a family of car thieves, but the CSIs must find the murderer before the rest of the family meets the same fate.

A night out for a friendly drink takes an unexpected turn when Danny and his rookie cops are caught up in a shooting.

The CSIs investigate when the recently paroled brother of a young basketball prodigy is implicated in a murder.

The CSIs investigate when a fraternity prank goes awry on Halloween and a pledge master is left for dead in an open grave.

A video of a high school party causes the team to wonder if too much weight on a porch caused the death of a girl. Jo has to deal with her former partner bringing memories of her last F.B.I. case.

As the CSIs investigate the assassination of a judge, Jo comes face to face with a criminal from her past.

When an important witness turns up dead, Det. Jo Danville is caught up in the dangerous investigation of the suspected rapist who was freed on her and her colleague's Frank Water's watch in D.C.

The team investigates a cage fighter's brutal murder and the possibility that he was killed by his stalker.

A home invasion investigation becomes more complicated when the victim's family turns out to be less perfect than they originally seem.

The CSIs investigate when a role-playing game turns lethal, with one player falling victim to a bona fide killer and the other kidnapped and held for ransom.

Two seemingly unrelated deaths share a surprising connection.

Mac and the team are deeply affected as they must investigate the murder of one of their lab techs who found murdered on the stairs of a vacant brownstone. The building was the scene of an unsolved murder of a famous socialite in 1957 and the scene was staged so that everything matches the previous case. Also, Mac's relationship with Christine continues to grow as he joins her for a family party

The CSI unit finds itself immersed in the world of competitive video gaming when they discover a murder may be related to a high-stakes tournament

The team is surprised by an explosion after a wave of brutality threatens a small New York City community when a body is found dismembered and strategically left out on four street corners.

The CSIs are called to a Brooklyn housing project to investigate the murder of a successful businessman who still felt the pull of his old neighborhood.

Mac fights for his life after getting shot.