After Horatio goes the extra mile to save Natalia, the team resume their hunt for an escaped serial killer.
Jane convinces Lisbon to take on a case as a favour to an old associate who stands accused of murder. The consultant initially thinks that animal activists are to blame for the crime, but begins to doubt his instincts when a complex web of deceit unravels.
The investigation of Chief Boden intensifies, so the pressure is on Firehouse 51 to find evidence that could clear his name.
Patterson questions Boden's ability to lead the firehouse as the trial approaches, Brett and Chili find an unconscious man in a garden, and Otis tries to fill his social calendar.
Patterson steps in as chief, and Dawson becomes a target of the conspiracy. Also, an act of violence changes Firehouse 51 forever.