Holmes and Watson face their greatest challenge yet after a murder investigation threatens to destroy their partnership.
Police chief Kevin Garvey tries to maintain a sense of normalcy in his strained community; Tom Garvey gravitates toward a cult; tension in Mapleton escalates.
When Bull assists the US Attorney's office with a manslaughter trial against a real estate magnate, his penchant for winning goes into overdrive as he realises the defendant is trying to use Diana to antagonise him during the proceedings.
Bull represents Hank Alston, a child recovery agent charged with fraud for not having documented proof of his covert work; Izzy wants Benny to consider hitting back at his opponent in the district attorney race.
When a female English teacher is found stabbed to death, Briscoe and Green uncover a love triangle involving a scorned teenager and her lover.