Sacramento Assistant DA Kelly Flower is shot dead at home. her recent cases include that of smuggler Hank Draber. Patrick Jane guesses at first sight contractor Cale Sylvan is a psychopathic serial killer, whose aliases and bank account suggest he got paid for each murder. He devices entrapment which yields trophy proof. But stickler judge Hildred dismisses the case when the defense proves Jane illegally searches Cael's home, rejecting all evidence as a 'poisoned tree'. The team keeps tracking him while Lisbon is suspended. Several surprise crimes follow, including Sylvan's, presumably ordered by his client in the Flower case.