Valentina de Angelis

When they are given the Social Security number of a teenager who was killed two years ago, Reese and Finch begin to question the infallibility of The Machine. Meanwhile, Finch flashes back to The Machine's origin and how it was developed.

Frank is put on the spot when a supporter for the mayor elect is found dead and Jamie goes on his first undercover assignment.

During a blackout, a panic-button alert sends Detectives Ed Green (Jesse L. Martin) and Cyrus Lupo (Jeremy Sisto) to the home of a high level corporate executive, where they find a murdered housekeeper and his missing wife and daughter. Suspect Marty Dressler (guest star Patrick Stump, "Fall Out Boy"), an employee who works in the company's IT department, leads the detectives to the murderous plan. Also starring: Sam Waterston, S. Epatha Merkerson, Linus Roache, and Alana De La Garza.

When an FBI agent who was working undercover is found brutally murdered, the CSI team is called in to assist the victim's partner in finding the killer. (TV-14)

When news of a high school house party goes viral, resulting in overcrowding, a collapsed porch and a teenage girl's death, the CSIs must use social media to uncover the truth about how she died. Meanwhile, Jo's final case at the FBI returns to haunt her. (TV-14)