They’ll kill you, and I’ll be here in the woods all alone and abandoned.

Nick goes to the trailer and goes over his ancestors’ journals, trying to figure out what they took from 13th century Constantinople and where they buried it.

At a ranch outside of Portland, owner Robert Hadley and his ranch hand, John, patrol the lands on ATVs. John comes across two dead cows and discovers that someone has been mutilating them. A glowing humanoid figure crawls up and John goes for the rifle on his ATV. They struggle and John ends up impaled on a fence post on the back of the vehicle. The creature runs off as Hadley pulls up, tangling itself briefly on a barbed wire fence.

As Monroe and Rosalee clean up after supper at his place, they talk about how his parents and the fact that they want to come visit. Monroe points out that it would be awkward given that Nick is currently staying there, but Rosalee figures that Nick will understand. When she suggests that the Grimm could find somewhere else to live for the two weeks, Monroe worries that Nick might not be able to handle it given his personal issues with Juliette. As the couple kisses, Nick barges in and asks for Monroe’s help. He finally realizes that he was interrupting something and apologizes, going up to his attic room. Rosalee suggests that Monroe help their friend and agrees to meet him the next night at her place.

When Monroe checks on Nick, the Grimm is studying the key. When Monroe sees the map impression that Nick made, he runs downstairs and finds a map of Europe that his ancestors made. The map matches one of Schwaben, Bavaria, and Nick explains that seven of his ancestors found some unknown treasure in Constantinople during the Crusades and locked it away to keep the Royals from getting it. When Monroe wonders where the other keys are, Nick admits that he doesn’t know but says that there is someone who does.

At home, Juliette is looking at a photo of her and Nick kissing at a Christmas and tries to bury herself in the moment. She remembers how she and Nick both finally admitted that they love each other and kissed under mistletoe.

The glowing Wesen, Vincent, goes back to the barn where his mate, Jocelyn, is suffering from labor pains. He gives her the meat he harvested from the cows and she eagerly eats it. When she notices that he’s cut from the barbed wire, Vincent assures her that it’s nothing and worries about her. Jocelyn says that she’s fine for the moment, but worries that they’re not safe hiding in a barn.

The next morning, UFO hunter George Lazure is listening to the police scanner and hears a report about John’s death and the alien sighting. He revs up his RV and starts driving toward Portland.

Vincent discovers that their car won’t start and tells Jocelyn to stay there while he gets another vehicle.

When Renard arrives at his office, Nick is there and asks about the seven keys. Renard explains that the Royals tortured one of the seven Grimms to get his key, and spent the next 600 years and much bloodshed obtaining three of others. Neither he nor his family know where the remaining two keys are. When Nick wonders what the Grimms hid, Renard admits that there are dozens of rumors but no one knows for sure except that it is allegedly an item of great power. The captain insists that they can’t let his family get the relic and asks Nick if he trusts him. Nick says that he trust Renard as much as Renard trust him. Before they can pursue the matter, Wu comes in and tells them that the sheriff has requested their help with the ranch hand’s death and the cattle mutilations.

Nick and Wu drive to the Hadley ranch and talk with the owner. Sheriff Doug Parcell and the local vet, Dr. Kevin Lavalle, are examining the crime scene. Parcell points out that John was shoved onto the fencepost with considerable force, while Hadley describes the ranch hand’s attacker as an alien. Lavalle informs them that the cows weren’t butchered, and Nick works out where the killer fled. He and Wu check out the fence and find the piece of skin, and they head back to the ranch. George pulls up and eagerly asks if there are any photos of other evidence of aliens. He explains that he’s a UFO hunter and that there have been a series of similar cattle mutilations across the country. Nick and Wu quickly duck him and drive off.

A local woman, Maureen Rodriguez, is driving through the woods when Vincent in Wesen form steps out into the road. She swerves to avoid him and goes off the road, and he reaches into the truck and grabs her.

George shows Hadley drawings of glowing bald aliens and Hadley confirms that was what he saw.

Vincent takes the unconscious Maureen back to the barn rather then leave her behind and risk someone finding her. Jocelyn worries about leaving the woman there, but Vincent tells her that they need to focus on the baby.

George checks out the barbed wire and finds some of the Wesen’s blood on the ground.

Dr. Harper analyzes the skin sample and calls Nick in. She demonstrates that it contains bioluminescent enzymes similar to those found in fireflies, and will trigger when the animal is agitated. Harper is unable to confirm if the skin sample came from an animal or a human. Meanwhile, Wu calls Nick and tells him that Purcell called to report another disappearance.

Vincent is driving Jocelyn away in Maureen’s truck but his mate starts having labor pains and asks him to pull over. As they wonder what to do next, Vincent spots an access road with a gate and moves it aside. They spot a cabin down the road and they go inside, and Jocelyn complains that she needs more to eat.

Juliette visits Monroe after making sure that Nick isn’t there. She shows the Blutbad the Christmas photo and says that she can remember everything that happened that night.

Purcell finds Maureen wandering on the road and brings her in. Nick questions her and confirms that her truck was taken near the Hadley ranch, and that an “alien” attacker her. Purcell has found the thieves’ original car and they’re trying to identify it. Meanwhile, Nick has Wu check the pattern of the cattle mutilations.

Juliette admits that she’s worried that, while she loves Nick, he can’t love her given how she’s treated him during her amnesia. Monroe assures her that Nick still loves her and suggests that she be honest with the Grimm about what he’s remembering. Juliette says that she’s not the same person and ask Monroe to keep her secret, and then asks him what a Grimm is. Monroe hesitates and then finally says that a Grimm is someone who can see what others can’t. When Juliette remembers Nick using the same words to tell her the same thing, Monroe admits that Nick is different.

After mapping the sightings, Wu tells Nick that the cattle mutilations started in Nebraska two weeks ago and have been moving northwest.

George checks out the barn where the Wesen were hiding earlier and finds more of the blood. He gets a call from a buyer who tells him that they have four parties bidding and can make a fortune if they can sell a set of three. George, a Raub-Kondor Wesen, transforms and angrily tells the man not to call him again, and that he’ll do what he can.

Nick checks the journals at the trailer and finds a page describing a Gluhenvolk, a bald glowing Wesen that looks like a traditional UFO alien. As he contemplates the drawing, Wu calls to tell him that the ovaries were taken from the cows in each mutilation.

Nick goes to the apothecary and shows the entry to Rosalee. She tells him that Gluhenvolk are all but extinct because people treasured their glowing skin, and they’re considered a good luck sign. When Nick mentions the ovaries, Rosalee explains that pregnant Gluhenvolk have a craving for ovaries. Checking the pattern of attacks, Rosalee says that the female must be ready to go into labor, just as Monroe arrives.

Vincent goes out to find more ovaries for Jocelyn.

Nick, Monroe, and Rosalee go over the maps of the area and determine roughly where the Gluhenvolks are hiding. The two Wesen insist on going with Nick so that they can save the Gluhenvolks from extinction.

As night falls, George patrols the woods and is able to find Vincent due to his enhanced vision in Raub-Kondor form. He loads a compressed-air rifle with special bullets and goes after his prey. Meanwhile, Nick and the others find the hunter’s RV and search inside. They find a skinning table and a collection of the special bullets, and Rosalee explains that the drug in them would kill a Wesen but keep him from transforming back to human upon on his death, for up to eight hours. They realize that George plans to kill the Gluhenvolks, take their skins, and sell them. Nick figures that since they didn’t pass the stolen truck, the Gluhenvolks are somewhere ahead of them and they continue their search. As they drive down the road, they spot the access road.

As Vincent harvests more ovaries, George shoots at him but misses and hits the bag holding the organs. Vincent runs off, glowing.

Nick, Monroe, and Rosalee go to the cabin and Jocelyn begs them not to hurt her. Before they can explain, her water breaks and Rosalee does what she can with the supplies at hand. When Nick goes to get his first aid kit, Vincent sees him and barges in. Rosalee assures him that they’re to help and manages to deliver the baby. George kicks in the door and the Wesen all woge. As the hunter prepares to shoot them, Nick distracts him by saying that he’s a Grimm and Monroe tackles the Raub-Kondor. George manages to knock the Blutbad back, but Nick grabs the hunter’s own rifle and kills him with it.

The next morning, Nick and the others wish Vincent and Jocelyn well. The couple explains that they plan to join a small community of Gluhenvolk in Alaska and drive off.

A SERT team gets an anonymous tip from Nick to check out the cabin. They find George’s corpse, in its Wesen form, in the cab of the stolen truck, and assume that it’s an alien. As they back away, the drug wears off and George reverts to his human form.