The beast was simply the Call of the Wild personified... which some natures hear to their own destruction.
Hank, a patrol officer, and his partner get a call about gunshots at a home. When they arrive, Hank and his partner discover that the place has been torn up. Two men are inside, one dead and one wounded. As they call in an ambulance, Hank hears someone outside. He runs after the man, Craig Ferren, and brings him down. Craig insists that the two men were monsters that were planning to eat him.
Hank is reading a newspaper about how Craig is being executed in 36 hours. He tells Nick about the arrest and how Craig shot the two men, Johnny and Miles Kreski, in their home. Craig was an Iraqi War vet suffering from PTSD and was convicted and sentenced to death for Miles' murder. Now that Hank knows about the Wesen living among them, Hank wonders if Craig's claim that the Kreskis were monsters is actually true. Since Hank's testimony helped convicted Craig, Hank wants to determine if the man was innocent and Nick agrees to help him.
Back at the station, the officers review the report. In Craig's statement, he claimed that the Kreskis were cannibals. Nick warns his partner that they will need actual evidence, not just his testimony as a Grimm, to confirm that Craig is innocent. Hank remembers that Robert Anderson was the investigating officer and now works with the Feds, and suggests that they talk to him.
A drunken Renard wakes up in his bed when his phone rings. It's a call from the station warning him that he's late, and Renard tells the caller that he'll be in soon.
Anderson meets with Hank and Nick and insists that Craig was guilty. He wonders why they're so interested in a closed case and they're unable to explain the reason for their suspicions. Anderson assures them that he did a thorough investigation of the Kreskis, who were well-liked in the community. Nick wonders if he dug up the brothers' backyard and Anderson says that he doesn't, but assures Hank that Craig was guilty and that he bears responsibility for the murder, not Hank.
Juliette invites her friend Elisha over and she talks about her situation with Nick. When she hesitates, Elisha realizes that Juliette has feelings for another man. Juliette admits that she barely knows the man.
Nick and Hank go to see Monique Dyson, Craig's girlfriend. She's reluctant to talk to the man who helped convict her boyfriend but Hank assures her that they've ran into similar cases and want to help Craig while they can. She invites them in and explains that Craig had issues because of his time in Iraq but he wasn't a murderer. She's sure that Craig believes what he saw was real and is still haunted by it. Craig eventually tried to break it off with her but she kept all of his letters and has refused to give up on her.
Next the partners meet with Grant Hoschen, Craig's court-appointed attorney. Grant insists that he did what he could for Craig and that he never found anything to substantiate Craig's claims that the Kreskis were killers. He shows the detectives drawings that Craig made of what he claimed to see and admits that the judge laughed them out of court. Nick and Hank go to the trailer and look through the journals to find anything matching Craig's sketches. They eventually find a journal entry about the Wendigos, a local Wesen that feed on human flesh and are almost completely immune to pain. According to the Grimm who encountered them, the Wendigos dig holes beneath their lairs to use as larders.
Hank and Nick visit Craig in prison. As they go in, Nick notices that a large percentage of the prisoners are Wesens, including some that he's put away in the past. When they talk to Craig, he figures that Hank came there to try and clear his conscience. Hank insists that they want to clear Craig's name and explains that Nick is an expert in cases like the one Craig experienced. Craig still refuses to cooperate until they show him the sketch he made of the Wendigos and the sketch from the Grimm journal. Nick says that the creatures Craig saw were Wendigos and that they do exist, but Craig admits that it doesn't make a difference. He has no evidence to back up his claims, and describes how when he went to the house to make some repairs, the Kreskis said that they were having him for dinner. Craig thought it was a joke but they said that they were going to eat him. When he tried to leave, they transformed and attacked him, and Craig used the gun in his toolbox to shoot them and then ran.
As Hank and Nick leave, they realize that they'll need evidence. The detectives figure that the Wendigos must have left the remains of their victims beneath the house and drive there to check it out. However, they discover that someone has built a convenience store over the site of the house.
Renard calls Juliette and apologizes for kissing her the other night. He warns her that it's a symptom worse and suggests that they both meet with someone he knows who can help them. Juliette agrees and Renard prepares to give her directions to the spice shop, but Wu interrupts him and Renard tells Juliette that he'll get back with her later.
As they check out the convenience store, Nick figures that they can use sonar to detect any bodies buried beneath the foundation. With time running out before Craig's execution, they go to see Renard, who is meeting with DA Lauren Castro. She already knows about their visit to Craig and asks what they're doing. They admit that they have nothing definite and that Craig definitely shot and killed a man, and a satisfied Lauren leaves. Hank points out that she convicted Craig and that his innocence could threaten her run for mayor. Renard agrees with Lauren, saying they don't have much, but agrees to back them up if they can find evidence to support their claim.
Once the detectives are alone, Hank apologizes to Nick for dragging him into the case, but Nick tells him not to worry about it. They try to track down Johnny Kreski, figuring that they may be able to provoke him into going Woge so they can confirm he is a Wendigo. Nick warns his partner that it still won't be enough to clear Craig's name, but Hank figures that Johnny is still killing and eating people and burying them beneath his new residence. As they go over Johnny's record, they discover that he has an outstanding warrant against him for missing jury duty. They also get a list of previous addresses and go to work.
At home, Johnny is making a stew... containing human body parts.
Nick comes home as Juliette reads about the symptoms of obsessions. She asks what he remembers about the night that she came out of her coma and he admits that he doesn't remember much. Juliette describes how she had dreams of something being taken away from her, and wonders how something could cause her to forget just one person. Nick says that it's the cat scratch but Juliette doesn't believe it, pointing out that she's had plenty of cat scratches in her job. Juliette also remembers being at Monroe's but not why she was there, and standing in the rain crying. Nick admits that he was there with her and knows why she was crying. However, he refuses to explain, saying that it wouldn't make any sense to her. Angry that Nick is keeping secrets from her, Juliette storms off.
As Craig waits for his execution, he looks at his sketch of the Wendigos and remembers how the Kreskis attacked him in their true forms.
The next day, Nick does some digging and confirms that at each of the Kreskis' previous addresses, there has been a sharp rise in missing person reports. He and Hank discover where Johnny is currently working and go to talk to his manager. The manager directs them to the back where Johnny is working, but he refuses to talk about Craig. Hank gets in his face, telling Johnny that they know he's a Wendigo, and Kreski goes Woge where Nick can see him. Johnny insists that Craig is the monster and is going to die for killing his brother. He angrily walks away and Nick tells Hank what he saw. They then go to the manager to get Johnny's address.
Rosalee calls Monroe at the spice shop to let him know that everything is fine with her aunt and she'll be back in a couple of weeks. Renard comes in and Monroe tells Rosalee that he'll get back to her. The captain then explains that he can bring in the person he's obsessed with and wants Monroe to close the shop so that they have privacy. Renard wants to know how long the consultation will take and Monroe admits that he can't know without talking to Renard and his obsession.
That night, Hank and Nick go to Kreski's home and go in, figuring they have probable cause from the outstanding warrant. They search inside and find a trapdoor beneath the refrigerator.
The warden comes with the guards and takes Craig to the execution chamber.
Hank and Nick search the cellar beneath Johnny's house and find buried corpses. They're unaware that Johnny has pulled up outside. They figure that they have enough to stop the execution and Hank climbs up first to call Lauren. Johnny attacks him and they knock over the refrigerator. It hits Nick as he climbs up, knocking him down into the pile of corpses. Hank and Johnny struggle and Hank manages to shoot the Wendigo in the side, forcing him to run off. He moves the refrigerator and helps Nick up, but they realize that the gunshot won't slow their opponent down.
As Craig is led into the execution chamber, he sees Monique in the gallery with the other observers.
At her office, Lauren rehearses her press statement about Craig's execution and her role in it.
Hank finds a trail of Johnny's blood and insists that Nick call it in while he captures the Wendigo because it's his case. Nick reluctantly agrees and goes inside to call Lauren, while Hank follows the blood into the woods.
The guards prepare Craig for execution by lethal injection.
Nick calls Lauren's office but misses her just as she leaves. He tries her cell phone and finally gets through, and explains that they have evidence confirming that Johnny tried to kill Craig and the shooting was in self-defense. He suggests that she get a warrant to excavate at the convenience store. However, before Nick can convince her, the Wendigo leaps through the window and attacks him. Nick holds his own and Johnny realizes that he's fighting a Grimm. He leaps out a window but Hank is waiting outside and orders him to surrender. Johnny charges toward him and Hank has no choice but to shoot him down. Nick tells Hank about the call to Lauren and they realize that they're out of time.
As the execution begins, Warden Stocker received a call from the governor ordering a 12-hour stay of execution.
Later, the police dig up the convenience store floor and discover dozens of partially-consumed corpses.
Later, Hank and Nick meet with Renard and Lauren. She wonders how she should announce Craig's innocence but they leave it up to her since she called the governor on Nick's advice. Lauren releases a statement congratulating the Portland PD on exonerating Craig and taking some of the credit herself.
Hank goes to see Craig in prison and the man thanks Hank for clearing his name. He wonders why Hank believed him when no one else would and suspects that Hank saw the same thing he saw. Hank doesn't confirm it but simply says that there are things that they don't understand, but they still exist. Craig asks for the truth and Hank tells him that it's a long story.
Monroe closes the spice shop and draws the blinds, and waits in the back for Renard to arrive. Renard brings in Juliette but they give into the spell again and kiss... just as Monroe comes out and realizes that Juliette is involved.