Walt and Vic find the dead body of a shepherd and his dog in the hills. The victim's name is Marko Vayas, and he is a member of the local Basque community, a group that immigrated to Wyoming from the mountains between France and Spain during WWII. Suspecting that Marko and his dog were poisoned, Walt begins an investigation.
Walt tracks down Marko's brothers, Costa and Sal, as well as Costa's wife, Amaya. The Vayas identify the subject of a photo found in Marko's cabin as a mail-order bride Marko had wanted to bring to Wyoming from Ecuador before they talked him out of it.
Walt finds a local matchmaker named Jeremiah Rains who is able to identify the woman as Rosa Marquez. Unbeknownst to his family, Marko had married Rosa a month earlier. Jeremiah claims that he doesn't know where Rosa is.
Meanwhile, the Ferg finds himself accidentally supporting his boss' competition when Branch drags him to a fundraiser. A photo of Branch and the Ferg ends up in the newspaper, so the Ferg apologizes to Walt. He makes it clear he doesn't support Branch, but Walt shrugs it off.
Vic finally delivers Walt's present from Lizzie after Walt comes across it in Vic's desk. Walt tries to ask how long Vic has been holding on to it, but he is interrupted and she runs away before he can find out.
Walt and Vic track down Marko's bride, Rosa, in a hotel room, and find Jeremiah there as well. He tells them that he was just protecting his business by covering up for Rosa, and swears she would never kill anyone. Rosa tells Walt that Marko was planning on selling his part of the Vayas family land in order to buy a house for himself and his bride.
Walt confronts Marko's enormous brother, Sal, with this information, but Sal refuses to believe it. Sal shows them a series of underground springs that dot their land, and Walt realizes he may have found the source of the poison that killed Marko. Sure enough, a spring close to the spot where they found Marko contains a sprig of hemlock.
Branch visits his benefactor, Jacob Nighthorse, after discovering that he is on the board of a lumber company that is trying to buy the Vayas' land. Branch is concerned that having a body turn up in the middle of a business deal could look bad. Jacob tells him that they were close to making a deal with Marko, so his death is a major setback. Jacob asks Branch for information about the case, and Branch refuses to tell him, but Jacob makes it clear that he isn't funding Branch's run for Sheriff because he likes him.
The Ferg is showing the team an elderberry plant, which looks similar to hemlock, when a call comes in from the Big Pines Lumber Company. Sal is at the site fighting the lumberjacks. On their trucks are trees clearly marked with arborglyphs. Walt and the team manage to get Sal locked up, where he tells them that he had never been offered a deal for his part of the land. Walt doesn't think Sal is the murderer; poison is a coward's weapon, and Sal is no coward.
Walt goes to Costa's house and finds that it's been trashed. There's no sign of Costa or Amaya, but there is a barking dog tied up outside. Walt unties the dog and follows it in his truck as it heads straight for its master. He finds Costa holding Amaya's head underwater in one of the springs. He tackles Costa, and Vic grabs Amaya. Walt holds up a piece of hemlock he found in the water, and tells Amaya she'll be dead in minutes, but he's not calling an ambulance until she talks.
The gamble pays off. Fearing for her life, Amaya admits that she poisoned Marko. She knew he was going to sell, and without his third of the land, their sheep would die and they wouldn't be able to make a living. She was trying to hold the family together. Vic tells Walt that he's being crazy and they need to get Amaya to the hospital, but it turns out there was no hemlock in the water. Walt just had the elderberry sprig that the Ferg showed them. Amaya is in no danger.
Meanwhile, Cady is in Denver with Detective Fales. She wants to learn everything she can about her mother's murder. Fales shows her the alley where she was attacked, and a picture of the man who stabbed her. Fales says they found him dead with a broken neck. He apologizes, saying that this would be easier to hear if her father was telling it, but she just laughs. He tells her not to be too hard on Walt, since he had been dealing with these feelings for a long time with only his friend to talk to. He asks Cady what that friend's name was, and she says "Henry." As she leaves, Fales tells her to call anytime, but she tells him she won't be doing that. When another cop asks him who he was talking to, Fales reples, "She was either sent here by the prime suspect in my murder case to find out what I know, or she's my new best friend."
Walt goes to the Red Pony to talk to Henry. His sources have told him that Fales is investigating Henry. Walt wants to talk about what happened in Denver, as they have never actually discussed it. He asks Henry what happened. Henry says, "A good woman was murdered, a bad man is dead. End of story." He tells Walt that Fales can investigate him, but he won't find anything. Walt asks why, but Henry simply states, "For such a spiritual man, you have a surprising lack of faith."