The body of a middle-aged man is found in the elevator of a ritzy doorman building on the Upper East Side. Mac Taylor and Aiden Burn's initial investigation yields no bullets, no DNA evidence, and no motive. Could this be the perfect crime? Meanwhile, only a few blocks away, Stella Bonasera and Danny Messer investigate the murder of a witness being held in protective custody. The law enforcement officers on duty swear that the victim spent the night in a locked hotel room -- only to be found dead in the morning. From the heart of midtown to the outer boroughs, the New York CSI team must piece together the evidence and solve two puzzling crimes in the city that never sleeps.