As Christmas approaches, Bull is amused when he meets a 9-year-old girl who wants to hire him to help her divorce her parents, but he’s shocked when a judge appoints him her temporary guardian. Also, Marissa discovers disturbing information about her boyfriend, Kyle.

Bull and the TAC team help one of their own when Marissa’s restaurateur husband, Greg, is charged with involuntary manslaughter after one of his employees dies in a kitchen fire allegedly caused by negligence. During voire dire, Bull and Benny aim to select jurors who will believe the fire was an accident and not a pattern of irresponsible management.

Bull aims to raise reasonable doubt among the jurors in his friend Nathan’s trial when the man is tried for his wife’s murder and the prosecution’s case is based on circumstantial evidence.

Bull aims to convince a jury to put the law aside, when he represents a woman guilty of kidnapping her niece years ago to stop the girl's father from abusing her. During jury selection, Bull looks for people who believe that when his client abducted her niece, she was saving the young girl's life.

Bull defends a train engineer who has no memory of a fatal crash he allegedly caused, due to a brain injury he sustained in the collision.

Bull and Benny mount a difficult federal trial defense for a young mother accused of aiding and abetting her extremist husband in an act of domestic terrorism. When the controversial case makes news, Benny's commitment to TAC complicates his burgeoning political career.

The TAC team gets a rare glimpse into Bull’s personal life when his estranged brother of 13 years, Jacob Bull, unexpectedly arrives in New York. Also, TAC represents a financial investor accused by the FBI of running a Ponzi scheme with his father to defraud their clients of millions of dollars.

Bull puts aside his personal grievances to help AUSA Reilly, who prosecuted him for jury tampering, bring one of the world’s most dangerous drug lords to justice. As the pair enter into a hesitant partnership, Bull’s unconventional style clashes with the lawyer’s commitment to working by the book.