The body of a cancer research scientist is discovered literally frozen solid, baffling Crews and Reese. The crime scene suggests that an animal rights group took revenge on the doctor by switching out his oxygen tank with pure liquid nitrogen. As the detectives delve into the victim's tangled private life, they become increasingly skeptical about the identity of the murderer. Meanwhile, Crews is determined to prove Jack Reese was involved in his incarceration, and Ted asks Crews to act as a reference for a business school interview.

When a college student is found crushed to death at a wrecking yard, Detectives Charlie Crews and Dani Reese pay a visit to the victims fiancé and discover the young man was involved in a complex online love triangle in which everyone is hiding behind a fantasy identity. Meanwhile, Crews continues his investigation of Jack Reese by searching for the four cops found in his latest clue -- an old photograph of a slain police officer.