They'll kill you, and I'll be here in the woods all alone and abandoned.
At the trailer, Nick goes through the Grimm journals trying to determine what was taken from Constantinople in the 13th century… and what they buried.
In a field outside of Portland, two men drive out to check their cattle. One of them, a ranch hand named John, discovers that two of their animals have been mutilated. A bald glowing creature emerges from nearby and when John goes for his gun, they struggle and John ends up impaled on a fencepost on the back of his ATV. The ranch owner, Robert Hadley, pulls up, discovers that John is dead, and sees the glowing creature running away. It briefly gets tangled on a barbed fence, leaving a bit of its skin behind.
Rosalee is over at Eddie's house and they make supper and talks about his parents in New Hampshire. They want to visit for a couple of weeks but Eddie is worried that it'll be awkward since Nick is staying there. Rosalee suggests that Nick would understand and he could move out temporarily, but Eddie worries that Nick might not be able to handle being on his own. As they kiss, Nick comes in, says that he needs Eddie's help, and grabs a beer. He finally realizes that he's intruding and goes to his room, and Rosalee suggests that she and Eddie get together at her place the next night.
In his attic room, Nick studies the key as Eddie comes in. He assures Nick that one interruption won't hurt his relationship with Rosalee, and Nick shows him the key, one of six. Eddie grabs it and takes it downstairs, and says that he knows about the map. He explains that the key is used to open ward-locks and digs out an old map of Schwaben, in Bavaria. The map is similar to the one on the key, and Nick explains that seven Grimms found an item in Constantinople during the Crusades, something so dangerous that they locked it away from the Royals. Nick suggests that there's someone who might know where the other keys can be found.
Juliette looks at a photo of her and Nick together and tries to remember the Christmas party that they went to. She remembers talking to her friend Ron about how neither one of them has said their true feelings. They kiss under the mistletoe and Juliette remembers Nick telling her that he loves her, and her saying it back.
The glowing Wesen, Vincent, runs to a barn where a woman, Jocelyn, is laying in the hay. She asks for the cow guts and he hands it to her, and she immediately gobbles it down. Jocelyn notices that he's hurt but Vincent says that it's nothing. He checks to see that her pregnancy is okay and Jocelyn worries that they're not as safe as they thought.
The next morning, George Lazure is listening on the radio as the police report a possible attack and alien sighting at the Hadley farm. George starts up the engine and drives to Portland.
Vincent tries to start their car without success and then tells Jocelyn that they have a problem. He tells her that she'll stay there while he gets another car.
Renard arrives at his office and finds Nick waiting for him. Nick informs the captain that he knows that there are seven keys that lead to a buried relic. Renard confirms that the Royals have four of the keys, meaning two of them are unaccounted for. The Royals tortured one of the Grimms to give up the key, and then spent 600 years and considerable bloodshed to get the other three keys. The legends say that the relic may be a key to immortality, Mohammed's Sword, or a piece of the Cross. Nick wonders what they're going to do about it and Renard says that they have to keep his family from getting Nick's key. He explains that his family would be happy if he was never born, and want to stay out of his way. Renard asks Nick if he trusts him. Before he can respond, Wu comes in to tell them that they have reported cattle mutilations, a possible homicide, and an alien sighting.
Nick and Wu drive out to the ranch and talk to Hadley, who tells them what happened. The county sheriff, Doug Parcell, comes over and introduces the local vet, Kevin Levalle. Doug says that John was apparently pushed back onto a fencepost with considerable force, and Hadley insists that the attacker was glowing and ran off. Levalle says that there was no butchering, and Nick and Wu borrow their truck and check out the fence. They find the piece of skin and bag it, and head back to the ranch. George pulls up and tells them that he's a UFO hunter and that there have been similar attacks across the country. They tell him that they don't have any evidence and drive off.
Maureen Rodriguez is driving through the woods when she sees Vincent on the road ahead of her, glowing. She swerves to avoid him and goes off the road, and Vincent reaches into the cab to grab her.
George talks to Hadley and shows him photos of aliens. Hadley points out the one that he saw.
Vincent brings Maureen back to the barn and explains that he didn't want to leave her behind where someone could find her. Jocelyn worries that they're just going to leave her there, but Vincent insists that they need to think about the baby and tells her to be strong.
George checks out the fence and finds some of the Wesen's blood.
Nick takes the skin sample to Dr. Harper, who says that it's luminescent. The enzyme glows when the creature is agitated, and Harper admits that she doesn't know if it's human or animal. Wu calls Nick to tell him that Doug has called and reported that they have another disappearance.
Vincent is driving the woman's truck but Jocelyn says that something is wrong and asks him to pull over. She insists that she has to rest and Vincent spots an old cabin nearby. It appears empty and he drives over to check it out. They go inside and Jocelyn says that she's getting hungry again.
Juliette comes to see Eddie after confirming that Nick's car isn't there. She shows him the Christmas photo of her and Nick and says that she can remember everything about it.
The police bring Maureen in and confirm that her truck was stolen near the Hadley ranch. Doug found the broken-down car and they're trying to identify it, and Nick asks Wu to check the path of the cattle mutilations.
Juliette says that she can feel how much she loved Nick, but she's worried that given how she's treated him, she's not sure if he can return her feelings. Eddie assures her that Nick still loves her and advises Juliette to tell Nick what she's remembered. She says that she's not the same person anymore and asks Eddie not to tell Nick. Juliette then asks him one other thing: what is a Grimm? Eddie tells her the truth, saying that a Grimm can see things other people can't understand. Juliette remembers Nick saying the same thing, and Eddie says that Nick is different.
Wu tells Nick that according to the stats, the cattle mutilations started two weeks ago in Nebraska and have moved northwest.
George goes to the barn where Maureen was found and finds traces of blood. A man calls him and asks if George has found them, and George says that he's close and that Jocelyn is going to give birth. The caller says that he has four parties bidding and they can make a fortune if they have a set of three. George tells him not to call again and then reverts to his Wesen form of a birdlike Raub-Kondor.
At the trailer, Nick finds a reference to a glowing Wesen known as a Gluhenvolk. Wu calls to tell him that in each cattle mutilation, the ovaries were taken.
At the apothecary, Nick shows Rosalee the entry on the Gluhenvolk. She explains that they were hunted to extinction because collectors valued their glowing skin. When Nick mentions the mutilated cows, Rosalee realizes that there's more than one, and the female is pregnant. The male Gluhenvolk is hunting for his mate, who craves cow ovaries. Given the number of attacks, Rosalee figures that the female will go into labor. Eddie arrives and is impressed when Rosalee tells him that a rare Gluhenvolk has been spotted.
Vincent goes out hunting for more ovaries.
Nick, Eddie, and Rosalee trace the route and figure out where the Gluhenvolks are holed up. They insist on going with Nick so that they can help him with a near-extinct Wesen.
That night, George spots Vincent thanks to his heightened night-vision. He loads a compressed-air rifle with darts and goes after the Gluhenvolk. Meanwhile, Nick and the others pull up and spot George's RV. The Grimm knocks at the door but gets no answer, and has Eddie open it. They find a fleshing knife and a skinning table, and realize that George is using drugged darts that would kill a Wesen and keep it in its Wesen form for up to eight hours. Once George takes the skin and tans it, he'd have a valuable specimen to sell. Eddie grabs the darts and they drive ahead, looking for the stolen truck. As they drive down the road, Nick spots the cabin.
George shoots at Vincent as he finishes with a cow, but misses and hits the bag with the ovaries. Vincent runs off into the night.
Nick drives up to the cabin and Jocelyn hears them pull up, assuming that it's Vincent.
George confirms that he missed and looks around.
Jocelyn tells Nick and the others to stay away, begging them not to hurt her. She goes into labor and Rosalee tends to her while Nick goes to get the first aid kit in his car. As he comes back, Vincent watches from the shadows. When Nick goes in, Vincent storms in and Rosalee tells him that the baby is coming. Jocelyn successfully delivers her child... and George comes in. Vincent, Eddie, and Rosalee all Woge, and Nick tells George that he's a Grimm. Distracted, George hesitates and Eddie attacks him. The Raub-Kondor knocks him out, but Nick grabs George's gun and shoots and kills him.
Later, Vincent and Jocelyn leave with their baby, heading for a commune of their fellow Gluhenvolk in Alaska. Meanwhile, a SERT team closes in on the abandoned truck and finds George's corpse, in its Wesen form. As they back away, the drug wears off and he reverts to his human form.