When prisoners at Starkville jail are found savagely beaten - and in at least one case, dead - Jim goes undercover as an inmate to investigate. This would be easier if one of the prisoners hadn't recognised him.
When a young, ambitious Cuban lawyer-to-be is shot, suspicion turns on the police. When one of the arresting cops is shot, it's believed to be payback. But the situation is more complex, as Jim and Blair soon find out.
Someone is beating then killing criminals who got off on technicalities. The MO is identical to that of the killer who shot Cassie in her previous post. But he's in a maximum security prison. It can't be him - can it?
While Simon is recovering in hospital from being shot, he overhears a murder being planned - placing his life in immediate jeopardy. Meanwhile his substitute is trying to take down a major crime lord - by herself.
Childhood rivalry, two very different sorts of fatherly abuse, and the discovery of his friend's body in the woods when he was ten, combine in the present day to place Jim and his father in deadly peril.
Jim leaves for a solitary trip. Suspecting he's hiding the location of the perfect fishing spot, Blair and Simon track him, only to find themselves all caught up in an army and CDC lockdown of a town wracked by a sudden, mysterious disease.
Feisty, insubordinate Australian cop Megan Connor temporarily joins Cascade PD as an observer. However, she's not here by chance - she has her own agenda, and if achieving it means ignoring Simon and Jim's orders, so be it.
The murder of a friend of Jim's spurs an investigation into crooked FBI agents, Federal Witness Protection clients, and gung-ho Neighbourhood Watch vigilantes. Much amusement, shenanigans and violence ensues.
With half of Cascade's utilities companies on strike, police HQ is in chaos - made worse by a murder witnessed by a man who believes he's an angel. There's an animal loose in the air ducts. And Jim breaking Blair's trust is the final straw.
Blair encounters a woman who is having problems with her senses. He finds out she has Sentinel abilities, and helps her cope with her abilities just as he helped Jim. Unknown to Blair, she's a criminal, and her team is on a crime spree in Cascade, Jim is on the case.