The Native American legend of the Mishipeshu, an underwater panther, comes to life with Hank as its unwitting host.
The episode begins with a disturbing look into the future, where Nick and Hank are battling it out, though Nick is pleading for Hank to realize what's going on. Only Hank's not listening because... he's a Wesen?!
Not so in the present, where a very human Hank joins Nick for dinner at Monroe and Rosalee's house. The four of them try to make small talk without bringing up the Hexenbiest in the room but Nick says he doesn't want people feeling awkward. At the same time, he admits he can't just sit there and ignore that she's out there either, so he soon leaves. Rosalee, determined to reverse Juliette's condition, says there must be something helpful in the spell book and witch's hat Renard's mom used. There's no quit in Rosalee, either.
Juliette, on the other hand, doesn't seem so keen on getting her old life back. At a bar, she lets a stranger buy her a pair of drinks and even flirts a little before deciding against doing anything more and getting up to leave. Her suitor, however, isn't so quick to let her go. Juliette questions him on what about her he likes so much; is it her looks? When he says yes, she woges, taking out all of the bar's lights, and shouts, "How about now?" When the man tries to approach her again, she sends him flying with her hand. As he shouts about calling the police, Juliette calmly exits.
In a high school late at night, a janitor polishes the floors in silence until he hears an unusual sound. When he goes to check it out, his floor polisher turns on behind him. As he makes his way back towards it, an animal-like creature jumps out and attacks him. When Nick and Hank arrive the next morning, Deputy Farris, with whom they worked on the Phansigar case, is already there and shows them the janitor's mauled body. They speak to the school's principal, who discovered the body, and learn about a recent incident involving the custodial staff and a bullied Native American student. Racial slurs were found on the student's locker several times and only the custodial staff had access to the school after hours. But the school was never able to prove anything and the student, Simon, ended up dropping out when he turned 18. The principal doesn't know where he is now - but we do. When we see Simon wake up in the forest, his mouth is covered in blood. As he drinks water from a pond, his reflection is that of the animal that attacked the janitor.
At the precinct, Hank learns the janitor, Larry Killburn, was previously arrested for assault but had no recent troubles. Nick looks into Simon's past and discovers his dad, Gus, was murdered when he was five. Farris remembers the story: Gus was pulled from his truck and beaten to death while Simon watched. Gus's killers were also never caught. She suggests they go to the reservation and ask the tribe about Simon; they know her there. But before they can get going, Wu stops by and reveals Juliette has been arrested. Hank and Farris go on without Nick as he pays Juliette a visit in her cell. Nick still wants to work things out but Juliette admits that deep down, she blames him for what's happened, and she can't promise she'd never hurt him. A part of her also loves her new state and doesn't want to go back to the way things where. She reveals she only let herself be arrested to see if Nick would rescue her. Turns out, Nick has no problem leaving her locked up.
Hank and Farris meet with Hector, an elder member of the tribe. He explains that Simon recently moved onto the reservation to get more involved with his heritage. For the past three days, Simon's been out in the wilderness on a Power Quest, a search for his Native American spirit guide. Hector also sheds more light on Gus's death, calling the murder a hate crime that was never properly investigated. Nick calls Hank then with news about a second victim who was discovered mauled to death, mechanic Declan Henry Burke. At the scene, Wu finds Killburn's contact info on Declan's computer. Hoping to discover how the two men are connected, Nick, Hank, Wu and Farris sort through both men's contacts. Meanwhile, in the forest, a chanting Simon makes contact with his deadly animal spirit again. It rises from the water and enters Simon's body.
Matching Killburn and Declan's contacts yields a third name, Maxwell McClay, whose assault record mirrors the others'. Believing him to be either the killer or the third victim, Nick, Hank and Farris head to McClay's house. As they make their way to his front door, a gunshot goes off. McClay comes flying out of his living room window soon after. Simon, fully transformed into the beast, runs out of the house and straight into Nick. Nick assumes the creature is Wesen but Simon doesn't react like Wesen normally do. When Hank joins them, he tells Nick he can see the animal-like appearance, too. In the confusion, Simon climbs onto McClay's roof and runs toward the front of the house. When he jumps down, Farris also gets a glimpse of the beast. She tells Nick and Hank she just witnessed something she's only heard about in stories.
After studying Renard's mom's spell book, Monroe and Rosalee think they might have found a way to temper Juliette's transformation but they need to know how much of each ingredient was used to create the potion that turned Juliette into Adalind. Renard hasn't been able to track down his mother but he warns Rosalee only a skilled Hexenbiest should be mixing these potions. Luckily, he knows someone who might be able to help. Unluckily, Renard might be in need of help himself. While standing in line at a food cart, he notices that the man in front of him is carrying a wallet full of $100 bills. Unknowingly, Renard follows the man to his car, knocks him out and steals his wallet. When he returns to the precinct, he has no memory of what he's done and has no idea how the wallet got in his pocket.
Back at the reservation, Hector listens to Nick, Hank and Farris' descriptions of Simon and identifies the creature as the Mishipeshu, a horned water serpent panther. He explains that Simon's mother was from one of the tribes that believes in the Mishipeshu and that on his Power Quest, Simon could've tapped into it. In order to find Simon, they must figure out where he's going next but to do that, first, they'll need to enter the dream world. To do so, Hector performs a ceremony around a fire in a tent and gives Hank, Farris and Nick something to drink. When Nick goes to sip, however, Hector stops him, saying there's something different about him and that entering the dream world could prove dangerous. To help Hank and Farris find Simon in the dream world, Hector gives them tokens that belonged to Simon's mother and father. Shortly after, Hank taps into Simon's childhood memories and witnesses three men murdering Simon's father. As Hank narrates what he's seeing, Nick realizes that's the connection between the three victims: they're Gus's murderers.
When Farris begins to overheat, Hector has Nick bring her outside. Hank, overcome with Simon's memories, takes off running out of the tent and deeper into the forest. Hector explains that Hank is still with Simon but he knows where he's headed, to the spot where Simon's dad is buried. When Hank reaches Gus's burial site, a clearing in the woods surrounded by totems, he finds an injured Simon on the ground. His ankle is red and swollen from jumping off of McClay's roof. The Mishipeshu leaves Simon's body and enters Hank's, sending Hank fleeing again. By the time Hector, Nick and Farris arrive, Hank is long gone. Hector admits the Mishipeshu can sometimes be a vengeful spirit and that it must've abandoned Simon because he's injured. Nick realizes it's trying to finish what it started: it's going after McClay.
Thankfully, Nick, Hector and Simon are able to beat Hank to McClay's house. When Hank enters, fully transformed into the Mishipeshu, Hector tells the spirit it's no longer needed. Nick tries to approach Hank but he spooks the Mishipeshu, causing it to attack. As Hank pins Nick against a wall, Hector intervenes and blows a powder into Hank's face. The powder exorcises the Mishipeshu and it disappears into a wall. Hank has no memory of being possessed but he clearly remembers seeing Killburn, Declan and McClay kill Simon's dad. When everyone goes outside, where Farris is waiting with McClay, Hank loses his cool and threatens him. McClay is unfazed knowing there's no way to tie him to the crime but later that night, he meets the same grisly end as Killburn and Declan. The Mishipeshu never really went away - it just entered Deputy Farris.