The detectives investigate a strangulation murder that may be tied to one of Diane Russell's cases; Russell consults a doctor when she discovers a lump in her breast; Medavoy and Jones investigate an arson linked to two boys.

A woman survives the serial killer's attack, and her account prompts the detectives to focus on Carlin, his partner, and a bodyguard; Medavoy and Jones investigate when an off-duty officer kills a man; and McDowell comforts Russell during a biopsy.