When an environmental scientist, Dr. Oscar Silva, is poisoned during a global warming symposium, Detectives Cyrus Lupo and Kevin Bernard initially suspect competitors from Dr. Silva's field of study. It is soon discovered that Dr. Silva is involved in a messy custody battle with his wife's ex-husband, Phillip Shoemaker and the focus of the investigation quickly shifts to the victim's family. Meanwhile, the case becomes personal for Cutter as it stirs up unpleasant memories from his own past.