Nick, Hank and Wu race against the clock to find a Wesen that freezes to death in the cold while Juliette seeks revenge against Adalind.
As Nick sits at home alone and turns photos of him and Juliette face down, his former love sneaks up on a bloodied Renard in his bedroom demanding to know where Adalind is. Still reeling from his fight with Kenneth, Renard relents and gives her the name of the hotel where Adalind is staying. Having gotten what she came for, Juliette begins unbuttoning her top. Renard hesitates, but after Juliette promises this will hurt, he gives in and kisses her.
On an isolated road, a man's SUV breaks down, forcing him to go searching for help on foot. He knocks on an elderly woman's door and asks to come in so he can use the phone. The woman, who is on the phone with her daughter, doesn't let him in after her daughter suggests it's not safe and instead offers to call a tow truck on his behalf. This angers the man, who goes to the back of the house and breaks in. He knocks the woman to the ground, all while she's still on the phone, and woges into a snakelike Wesen. He bites her shoulder and sucks, turning the woman pale and frosty. When he leaves, she's dead and frozen solid.
When Nick and Hank arrive, Wu shows them the woman's body and says the only thing taken was her car. The house is 72 degrees inside and yet the body is covered in frostbite. After interviewing the woman's daughter, Nick and Hank have Wu search for the man's abandoned car while they hit the road. A short time later, Wu calls and says the victim's car was spotted leaving a gas station. The police set up a roadblock in the direction he's traveling while Nick, Hank and Wu make their way over to intercept the driver. When the man sees the roadblock, he turns the car around and attempts to escape but Nick, Hank and Wu are in the way. Seeing no way out, he stops the car in the middle of the road and goes running into the woods. Nick, Hank and Wu follow, and thanks to Nick's Grimm hearing, they quickly catch up to him. The man woges and tries to attack Nick, but he quickly collapses to the ground, shivering.
At the precinct, Nick and Hank identify their suspect as North Dakota resident Knute Gunderson. While they can't prove how he's freezing people to death, they do have him on charges of home invasion, assault and theft. But the case takes a weird turn when Wu runs in and says something's not right. In his cell, they find Knute frozen to death.
When Renard wakes up, he's alone in bed and still in terrible pain. He gets up and looks in the mirror and sees his wounds start bleeding again. Soon after, the bedroom begins to glow with a white light, and when Renard turns around, a pair of red hands comes lunging toward him. Renard grabs his throat, unable to breath, and falls to the floor.
Nick and Hank search Knute's abandoned vehicle and find three sets of fast-food wrappers and three packed bags. As it occurs to them that there are two more mysterious Wesen out there, a woman helps a freezing man into her car. She's a nurse and she's going to bring him to the hospital, but that's not what he needs. He woges and tries to bite her but she manages to get away. As she flees, he crawls out of the car, looking pale and frosty.
In need of bigger clothes, mom-to-be Adalind hits the shops accompanied by one of Kenneth's bodyguards. Juliette, watching from across the street, sees her check out the window of a store whose roof has two gargoyle statues on it. While Adalind considers going in, Juliette jiggles one of the statues loose with her mind and sends it crashing down. Kenneth's bodyguard saves Adalind just in time but not before she catches a glimpse of Juliette's reflection in the shop window.
Nick and Hank turn to Monroe and Rosalee for help identifying their mystery Wesen, and as always, the pair comes through. It's a Varme Tyv, a cold-blooded Wesen that can't generate its own body heat so it steals human heat to survive. Rosalee says ordinarily they're harmless but being caught outside must've driven him to kill. She adds that the Varme Tyv must've been headed for a hibernaculum, an enclosed space where Varme Tyv share their body heat to make it through the winter. Or "an animal heat orgy," as Monroe puts it.
Monroe and Rosalee step away when they hear the Spice Shop door open and find a shaken Juliette waiting for them. She needs their help but when Nick and Hank enter the room, Juliette grows angry. Monroe and Rosalee wonder what's going on, and Nick tells Juliette to explain. She does so by woging. As everyone processes what's happened, Juliette tearfully says she shouldn't have come, that they all had a hand in what happened to her. When she leaves, Nick admits there's no way to undo the transformation and that he and Juliette are no longer together.
Wu's call breaks up the tense moment and summons Nick, Hank and Monroe to the spot where the second Varme Tyv was found frozen. At the scene, they learn this one was Knute's brother. While Wu tracks down how many Gundersons reside in North Dakota, Nick and Hank look for a relative in Portland whose home could be the site of the hibernaculum. Their list narrows itself when a call comes in about another frozen body. The latest victim is a cab driver, and his cab was spotted taking off in the direction of only one potential Gunderson relative. The North Dakota P.D. fills in Wu on who they're looking for: Sven, Knute's other brother, who has a record and distinctive snake tattoos on his arms.
Adalind tries to convince Kenneth that he needs to kill Juliette before she can kill her, but Kenneth has other ideas. Now that Juliette's a Hexenbiest and presumably on the outs with Nick, she could prove an important ally in the search for Kelly Burkhardt. Sorry, Adalind, staying alive is solely on you.
At the Gunderson farm, Nick, Hank, Wu and Monroe find a host of cars parked outside but no sign of the stolen cab and no lights on in the house. They break in and find the place freezing cold - until they make their way into the living room and find a particularly hot spot. Underneath a rug is a trap door that leads them to the basement, where they discover a large group of Varme Tyv coiled around each other fast asleep. Nick, Hank and Wu circle the group searching for Sven. When Wu spots him, Nick and Hank try to free him from the group without disturbing the others, but soon the entire group is stirring awake. As the Varme Tyv give chase, Nick, Hank, Wu and Monroe try to hide in the barn, but the Varme Tyv break down the door. Then, as quickly as they came, the Varme Tyv begin dropping; it's too cold for them outside. Realizing innocent people are going to die, Nick says they have to bring them back to the hibernaculum. One by one, he, Hank, Wu and Monroe place everyone back the way they were. They agree to pretend they never found this place and plant Sven's frozen body and the cab elsewhere in town.
With another case solved, Nick returns to his empty house and remembers the words of his Aunt Marie: "The misfortune of our family is already passing to you… I know you love Juliette, but you have to end it and never see her again." If only Nick had listened.