Detectives Mac Taylor, Danny Messer, Sheldon Hawkes, and Don Flack are called in to investigate a double homicide at a medium-security facility on Staten Island. Racial tensions turned the prison into a pressure cooker that finally boiled over in an all-too-lethal fashion, leaving two inmates dead. One of the killings is an open-and-shut case, complete with eyewitnesses; but the other, the murder of a former cop, defies easy answers. Initial investigation of the crime scene points to one cause of death, but the CSI team's scientific methods uncover something completely different – and wholly unexpected…On the other edge of the city, Stella Bonasera and Lindsay Monroe look into the murder of a young woman who worked at a popular Italian bakery in the Bronx. They find the perfect suspect almost immediately: a frequent customer who spent a lot of time flirting with the victim and who previously had been arrested for a violent crime. Yet Stella can't help but think that their perfect suspect is just a little too perfect for such a messy murder…Nothing is as it seems as New York City's dedicated crime scene investigators piece together the clues and examine the evidence to discover the true killers in their midst.