A London photographer takes some pictures of a couple in a park and discovers that he may have recorded evidence of a murder.

Amidst the neon lights and long shadows, dark threats continue to lurk in Sin City. Maxine Roby leads her brilliant team of Crime Scene Investigators as they use science to solve baffling cases. Catherine Willows returns to help the CSIs face off with a dealer of death who is planning to beat the odds in Las Vegas. This combined force will deploy the latest forensic techniques in order to preserve and serve justice in Sin City.