More and more she grew to love human beings and wished that she could leave the sea and live among them.

Two sisters, Sarah and Anna, hook up with two guys out on a fishing trip. Dan Hopkins ends up with Anna and Jake Barnes ends up with Sarah. As they party, Sarah notices her younger sister Elly hiding in the bushes, spying on them. Sarah excuses herself briefly while Anna and Dan go out into the water, and then confronts Elly. She tells Elly to stop trying to be something that she isn’t, and Elly reluctantly walks away. Sarah then goes out into the lake, removing his bikini top, and calls to Jake to come in with her.

Elly comes back despite her sister’s warning, while Jake swims out to Sarah. Once he’s facing away from the shore, Elly sneaks out and takes Jake’s cellphone, then goes back to the bushes and examines it with interest. Meanwhile, something under the water grabs Dan’s lake and starts dragging him under. Jake swims out to help his friend and another creature grabs his leg and pulls him down as well. Anna and Sarah watch, seemingly unconcerned. A few minutes later, Jake is floating in the water, unconscious. Elly swims out and pulls him to shore, her hands covered in webbing and her eyes turned silver. She administers CPR until he wakes up, and he stares at her transformed face in confusion. Elly runs off before Jake can ask her anything, and Jake calls to Dan but gets no answer from him or the girls.

Monroe is helping Rosalee move her things into his house and is somewhat overwhelmed by all of the stuff that she is bringing. He’s clearly uncomfortable, especially when it becomes clear he’ll have to take out some of his own possessions. As Monroe tries to figure out what to get rid of, Rosalee assures him that he can keep everything and they kiss.

Nick is heading out for work after a normal breakfast. He pauses and tells Juliette that he misses having an ordinary everyday life with her. Juliette asks him about the results of his physical and Nick tells her that the doctor sent an email and asks her to check for him.

Hank and Nick are soon called to the lake when Dan’s body turns up. They confirm that Jake reported him as a missing person and examine the body, and discover claw marks on the legs. They go to see Jake at his apartment and give him the news, and Jake tells them what happened. He admits that he doesn’t know the sisters’ last name or who it was that rescued him. Hank notices that Jake has the same scratches on his legs that Dan had and Jake confirms that the same creature attacked him.

Jake takes the detectives to the spot where he and Dan met the girls, but there’s no sign of them. As they look around, Nick hears Elly moving in the bushes thanks to his heightened hearing. He chases her but Elly dives into the lake and swims 50 yards in a matter of seconds. She turns back and Nick catches a glimpse of her Wesen features, and then she swims off into the distance. Hank and Jake run up and Jake just manages to see the girl and confirm that she was the one who rescued him.

Back at the station, the partners tell Renard what they’ve found and that they’re dealing with a new kind of Wesen. After they leave, Sebastien sends a photo to Renard of Adalind. Renard calls his spy, who tells him that Adalind is the one staying at the Sacher Hotel in Vienna. They figure that she is the one with the Royal baby and that she approached the missing Frau Pech to have the older woman find someone that she could sell it to.

Nick and Hank drop in on Monroe and Rosalee and describe the creature that Nick saw. Rosalee recognizes it as a Naiad, a tight-knit clan of Wesen who always live near water. Monroe is eager to go with them to the trailer and get out of the house, and Rosalee tells him to go. At the trailer, they find a journal of a Grimm who captured one of the Naiad aboard a merchant ship in 1755. The Naiad abducted one of the crewmen and later the Grimm captured her. The Grimm deprived her of water and kept her hidden from the crew, and she began to dehydrate. Despite that, she refused to tell what happened to the crewman and eventually died when deprived of water. Wu calls to tell the detectives that they’ve tracked the GPS on Jake’s phone and confirmed that it’s at the Anderson Marina near where Jake and Dan were fishing.

After the officers pick up Jake to make an identification, they drive to the marina. Jake stays with the car and watches with binoculars while the officers approach the houseboat where the GPS signal is coming from. The owner, Abel Mahario, comes out and asks what they’re doing there. He insists that they’re mistaken but Wu calls and it rings, giving them probable cause. Nick and Hank search the place and find the cellphone, as well as a photo of the three girls. Nick recognizes Elly from their earlier encounter and goes out to confront Abel. Abel tells them that his daughter is deaf and they can’t question her, and claims he has no idea how the cellphone got in his houseboat.

Sarah and Anna approach the houseboat and Jake spots them. He runs over and calls to them, but they pretend that they’ve never seen him. Meanwhile, Elly, who has been hiding nearby, slips into the water and watches as Jake tells her sisters that Dan is dead. Sarah insists that they were with Abel just as two other neighbors, Dominic and Jesse, come over. They demand to know what’s going on and Wu tells them to back off. When Sarah and Anna stick to their story, Nick and Hank take them in. When Abel objects, he briefly loses control and Nick sees his true Naiad face. Nick tells Abel to consider telling the truth and leaves with Hank and the others.

Once everyone has gone, Dominic and Jesse come over. He complains that the killed Dan and Dominic points out that Abel has forgotten where he comes from. Abel insists that he hasn’t and that their world died 200 years ago, and their fundamentalist crap is endangering all of them. The two men figure that Elly is responsible and tell Abel that she has to be “cut.” He objects and they knock him aside and leave.

At the station, Sarah refuses to answer Nick’s questions. He tells her that he knows that they’re Naiads and points out that her skin is starting to dry out. Sarah still refuses to talk so they go to work on Anna. She is also drying out but refuses to talk. Hank and Nick go to Renard and explain the situation, warning that the two girls won’t survive the night. Renard figures that they can’t give the Naiads any special treatment and that they’ll have to live with the consequences if they refuse to cooperate.

Abel comes to the station and confesses to Dan’s death, claiming the boys were trying to rape his daughters. However, Nick and Hank don’t believe him and Nick says that they want to get the people who are really responsible. Hank points out that Abel has a black eye and they pepper him with questions about the murder and where it occurred. Despite the fact that it’s clear he’s innocent, Abel refuses to change his story. The officers go back to Renard and suggests that they use Abel’s confession to put pressure on the girls to tell them the truth.

When Jake goes to his apartment that night, he discovers that someone has broken in. Elly comes up behind him and speaks her name, and indicates that she can read lips. Jake says that the police need to talk to her, but Elly leads him to the apartment’s pool and dives into the water. She transforms into her Naiad form and swims around the pool repeatedly, much to Jake’s surprise. He realizes that what he saw is real. Elly tries to shout a warning to Jake as Dominic comes up behind him, but it’s too late and Dominic knocks Jake out. Jesse grabs Elly and drags her out of the water, and the two Naiads leave with the girl.

At his home, Monroe finishes unpacking and takes out a Dutch rabbit statue from the last box. Despite the fact that he can’t stand it, Monroe tells Rosalee that they’ll put it up on the mantle. She admits that she can’t stand it either and tells him that he doesn’t have to try so hard. Monroe admits that there have been other women, but none that he considered moving in. When Rosalee wonders if he’s getting cold feet, Monroe says that he isn’t and she tells him that as long as they love each other, and tosses the statue in the box.

Nick and Hank tells the girls that Abel confessed to everything and they’re releasing them. Sarah finally breaks and tells them that Dominic and Jesse attacked the boys. With time running out before they need water, Nick takes them to the interrogation room to get the full story. Sarah explains that it’s time for them to start their families. Naiad men are sterile so Naiad women find human males to impregnate them. The Naiad men are then forced to raise other men’s children, leading to tensions. Dominic and Jesse come from a traditionalist clan and had arranged marriages with Sarah and Anna. In their tradition, the male Naiads kill the humans after they have sex with their wives. Jake calls Nick to tell him that Dominic and Jesse took Elly away, and Sarah realizes that they plan to cut her webbing: a traditional Naiad punishment that they’ll inflict at their home.

At the marina, Dominic and Jesse tie Elly up and try to submerge her so that she’ll transform, exposing her webbing so they can cut it. She transforms to her Naiad form but then reverts again before they can cut her. Nick and Hank arrive and Jesse slams Elly’s head against a cleat, knocking her out. Dominic attacks Nick while Jesse wraps an anchor chain around the unconscious Elly’s legs and shoves her into the water. Hank tackles Jesse while Nick knocks Dominic out and dives into the water. Thanks to his enhanced senses, he finally locates her and brings her to the surface. Hank handcuffs the two Naiad men and helps his partner out of the water, and tells him that he was underwater for several minutes. Abel and his daughters arrive and embrace Elly, relieved that she’s unharmed.

Juliette is at home reading the email from Nick’s doctor. The doctor reports that Nick’s metabolic rate is half that of a normal person, but he’s showing no ill effects. Another email comes in, signed “M”, and saying that it’s no longer safe in Europe since Eric was assassinated and the money has run out. Juliette wonders who “M” is.

Renard watches the funeral service for his half-brother Prince Eric and listens as the announcer says that the authorities are after an underground group that they believe is responsible for the explosion. Everyone is wondering who will take over the royal family.

At the station, Jake picks Dominic out of a lineup as the man who attacked him at the pool. He then turns to Hank and Nick and admits that he has no idea what Elly is, and wonders if she’s a mutant or a mermaid. When he says that Elly isn’t normal, Nick just tells him that it’s Portland and nobody’s normal.