In the Season 4 premiere, the team deal with the fallout from Branch's confrontation with Barlow; and Walt's crusade to bring Nighthorse to justice spirals out of control.
Walt's attention is divided between the discovery of new evidence in a personal case and the investigation into the murder of a caretaker at a former Japanese internment camp.
Cady makes a shocking discovery; at the same time, Walt's investigation of Nighthorse heats up, but not in the way he was hoping.
Walt's troubles with Nighthorse are further complicated by the discovery of a body in the luggage of a tour bus. Meanwhile, Henry makes a bold move to help a mother and son.
Walt finds himself drawn into an emotionally charged investigation involving an assault during an apparent robbery of a man married to a former soldier.
Volatile tensions erupt between local oil rig workers and the Cheyenne people when a young Native American girl is raped on the reservation.
Walt struggles to let go of the past as he and the team investigate a highway robbery perpetrated by people involved in a strange relationship.
A former suspect in a rape case ends up dead in another county, which strikes Walt and Vic as more than a coincidence.
Henry is troubled with new problems after his attempt at justice backfires, resulting in a new investigation for Walt.
In the Season 4 finale, the line between justice and the law gets even blurrier for Henry and Walt as their hunt for a killer intensifies.
Walt seeks closure for his wife's murder and Henry's case. Meanwhile, Branch is suspended but continues to investigate Jacob Nighthorse.
While Walt makes a breakthrough in the David Ridges case, Branch's conduct is worrisome. Henry has a setback in his trial. Vic decides what her future will be.
A farmer's death is investigated but a life insurance policy causes difficulties. Later, Sean gives Vic an ultimatum.
Walt forms an unlikely alliance after Vic and Sean are kidnapped.
A man missing for 30 years turns up dead. Later, Henry makes a risky decision.
Walt attempts to narrow the field of suspects in his wife's murder. Meanwhile, Branch's behavior causes trouble.
Walt and the team search for missing teenage campers.
Walt is asked to judge a pageant during an ongoing murder investigation. Meanwhile, Cady turns to an old friend for help.
Walt investigates the murder of a Russian adoptee. Meanwhile, Henry faces trouble in jail.
Walt deals with the repercussions from Henry's arrest and Branch's shooting. Looking for the shooter proves complicated when Branch reveals who shot him.
Walt and Branch investigate an apparent suicide that may be linked to Cady's accident. Walt and Henry must face up what took place in Denver when Detective Fales shows up with warrants.
A severed finger shows up at the station and Walt connects it to a new murder and a twenty year old armed robbery. Vic confides to Walt that she's being stalked.
Longmire links up the death of a game warden and a poached elk to an expensive supplement. Cady wakes up after Longmire concludes his sacrifice. Branch is closer to discovering what really happened to Cady.moreless
On Election Day, Walt and Branch see things with a new outlook as they race to find a hit-and-run driver.
An explosion on the reservation has the Cheyennes blaming an energy company's fracking. Branch hooks up again with Cady and finds some information he can use to his advantage in the election.