“Instantly, the priestess changed into a monstrous goblin-spider and the warrior found himself caught fast in her web.”

A fuschsbau, Ryan Showalter, is at an art gallery picking up women while his girlfriend Amy Lewis is out of town. He approaches one woman, Lena Marcinko, who is admiring the art and tries to flirt with her. She seems interested but then quickly leaves. Ryan follows her down the street and convinces her to go to his apartment. However, Lena quickly says that she has to leave. When Ryan persists, grabbing her and throwing her onto the couch, Lena grabs him and throws him down on the floor. She then transforms into a spider-like creature, and Ryan bites off her left index finger as they struggle. Lena soon gets the upper hand and spits digestive fluid into Ryan’s mouth, liquefying his organs. A few minutes later she leaves the building, crying.

Nick is at home working on the TV with Juliette when someone eggs the house. He grabs his gun and goes out to investigate, and finds the two boys responsible. Nick realizes that they’re eisbibers and they quickly run off when they see Nick. Back inside, Juliette talks about how she used to run across a creepy old man’s backyard as a kid until her father explained that the man had been injured in the war. Nick admits that they haven’t been the quiet neighbors next door and Juliette suggests that they could work on that.

The next day, Nick meets with Monroe to complain. Monroe points out that most creatures consider Nick a monster at worst, a curiosity at best. Nick is worried that he’s big news in the creature community and that Juliette could be in danger. Monroe asks him if he’s told Juliette that he’s a Grimm yet and Nick admits that he hasn’t. Nick gets a call to Ryan’s apartment to check out the murder. Amy came back to town and found the body, which has been entirely desiccated despite the fact it would have taken days. Ryan’s gold Rolex is missing and Amy has confirmed that Ryan was at the art gallery when she talked to him. The CSI tech finds a severed woman’s finger and it moves briefly when Nick picks it up.

The detectives go over the security footage at the art gallery and talk to the owner, Marta. She doesn’t recognize Lena from the footage but offers to get the invitation list. Hank and Nick then go to the morgue where Dr. Harper informs them that the victim had his organs liquefied via an acid that was forced down his throats. The killer then sucked the organs out by biting open Ryan’s abdomen. The detectives report to Renard and are informed that the print from the severed window turned up at a similar murder in Phoenix five years ago. A gold ring was stolen from the victim and they figure that the killer takes trophies. The tox report from the Phoenix killing indicates traces of spider venom in the acid used to commit the murder.

That night, Nick goes to his aunt’s trailer and finds a journal entry on creatures known as spinnetods.

At home, Lena dons a blonde wig from a collection that she owns. She looks at herself in a mirror, sobs briefly, and manages to gain control of herself. Lena then goes to a bar and approaches a man, Anton Mengers, who is eating alone. They go back to his hotel room and Lena kills him the same way that she killed Ryan.

Nick goes to see John Oblinger, one of the men watching him. John, an eisbiber, panics and tries to lock the door, but Nick easily gets in. John’s brother Bud comes in and they both insist that the meant no harm, but they had to prove that they actually knew a Grimm. Nick tells them that he has no intention of hurting anyone unless they threaten him or Juliette, and tells the eisbibers to make sure everyone they told gets the message.

A maid finds Anton’s corpse, unaware that Lena has slipped out behind her. The police are called in and Nick and Hank confirm that he was killed the same way as Ryan. A piece of black dress fabric is caught in Anton’s hand and they check the hotel security footage. Lena is on the recordings and they realize that she fits the description despite the blonde hair. Renard checks with the police in Phoenix and Albuquerque and determines that there were two more murders in Phoenix five years ago, and three murders in Albuquerque five years before that. The officers figure that it’s a ritual killing and that the murderer needs to claim a third victim.

Lena goes to a park and glances over the men who are jogging and playing. One man comes over to help her and Lena flirts with him… and then kisses him as their daughter, Sally, comes over, glad that her mother is there to watch her play soccer.

Nick visits Monroe and asks him about spider-creatures. Monroe identifies the killer as a spinnetod, a death-spider that kills after sex. He offers to connect Nick with a former spinnetod, Charlotte, who can give the officer more information.

At home, Lena has supper with her family. She gives the gold Rolex to her husband, Robert, and says that she loves him.

Monroe takes Nick to a home for retired creatures. He’s surprised that the elderly Charlotte looks so old, and she transforms briefly when Monroe explains that Nick is a Grimm. Charlotte is unimpressed, saying that a Grimm can’t do anything to her that time hasn’t already done. She explains that she turned her back on what she is years ago, and then confirms that the spinnetod has killed twice. The retired spinnetod tells them that if the killer doesn’t strike again in three days, she will age rapidly. When Nick wonders what she means, Charlotte tells him that she’s 26 years old. They can only reverse the rapid-aging process by sucking the life from young men, and they take no pleasure from it. Spinnetods are attracted to shiny objects, and she doesn’t wear any so that she can avoid temptation. When she admits that Monroe and Nick are starting to look appetizing, they make a hasty exit.

Back at the station, Hank gets a report that someone has reported the gold Rolex at a middle school. He and Nick go there and the principal explains that one of the students, Sally, traded him the Rolex for his mountain bike. They call in Sally and she admits that she stole it from her father. They go to the house and arrest Robert, and Nick sees Lena for what she really is. Hank notices that she has a bandaged finger, but when they ask her to remove the bandage, they discover that her left index finger is intact. At the station, they interrogate Robert but he insists that he got the watch at a swap meet. Renard tells Nick that they have nothing on him but purchase of stolen goods, but Nick insists that Robert knows something.

Lena goes out for the night, dropping Sally off with a babysitter to study.

When the lab reports come back, Nick and Hank discover that Lena’s left index fingerprint matches the one on the severed finger. Hank can’t explain it but goes to confront Robert. Robert admits that he’s a spinnetod as well and explains that he doesn’t know where Lena is or where she goes when she kills. When Nick wonders why he’s still alive, Robert explains that Lena truly loves him and can’t bring herself to kill him despite the biological compulsion.

Lena is taking a shower and looks in the mirror, and realizes that she’s started to age.

Nick and Hank take a squad back to the Marcinko home. Nick finds the wigs as well as Lena’s peeling skin in a wastebasket. The harbor patrol reports that they’ve found Lena’s car at the marina.

Lena has convinced a rich young man, Aaron, to take her onto his boat. As they kiss, they hear something moving outside and Lena convinces Aaron to go outside and check. Hank grabs him and gets him off the boat, and Nick goes below to confront Lena. He searches the ship and discovers that Lena has slipped out through a hatch. Nick goes after her and she jumps over the railing to attack him. He manages to shoot her before she can spit acid on him, forcing Lena to flee. Nick chases her along the pier to a trawler, hits her with a boom, and knocks her into a fishing net.

Later, Nick and Hank take Sally to her grandmother. She wonders what happened to her parents but the officers don’t have any easy answers for her. As they get in, Nick sees Sally transform into a spinnetod and realizes that it isn’t over.

Lena is in a jail cell, having aged dozens of years overnight.