”Instantly, the priestess changed into a monstrous goblin-spider and the warrior found himself caught fast in her web.”
At an art gallery exhibition, Ryan Showalter calls his girlfriend Amy Lewis and tells her that he just got there. She apologizes for not being able to be there with him since she’s on a trip, and Ryan glances at the attractive woman present while they talk. Once he hangs up, Ryan approaches an attractive woman, Lena, and makes small talk about the paintings. As they talk, Ryan’s face briefly changes into that of a fuchsbau. He tells Lena that he’s a collector and invites her to have a drink with him. Lena passes and says that she has to go, and Ryan follows her out. He comes up to her and flirts with her, and she finally goes back to his apartment with her. Lena immediately says that she has to leave, but Ryan says that she just needs to relax and kisses her. She says that he doesn’t understand and tries to leave, and Ryan grabs her and tries to rape her. Lena throws him to the floor but then transforms into a spider-like creature and spits digestive juices out of her mouth and into his. As they struggle Ryan bites off her left index finger.
A few minutes later, Lena is walking away down the street, crying.
Nick and Juliette are at home when two boys egg their house. Nick goes outside and realizes that they’re eisbibers. They run off when Nick draws his gun, and Juliette points out that they haven’t been the friendliest of neighbors. The next day, Nick talks with Eddie, who warns him that most creatures consider him a curiosity since they’ve never seen one of the “legendary” Grimms. Nick is worried that Juliette could be in danger and reluctantly admits that he hasn’t told her that he’s a Grimm.
Before Eddie can pursue the matter, Nick gets called to Ryan’s apartment. Amy returned to town from an audition and found her boyfriend dead. The body is desiccated as if it were exposed to the elements for days, but Amy has confirmed that she talked to Ryan the previous night. They find a severed woman’s finger next to the body and it twitches when Nick picks it up. The officers go over the security footage with the gallery owner, Marta, and she admits that she didn’t know much about Ryan. Marta doesn’t know Lena and Nick asks for the invitation list. They realize that Ryan followed Lena out and figured that he caught up to her on the street.
Dr. Harper calls Hank and Nick to the morgue to tell them that Ryan was forced to ingest a highly corrosive acid. His liquefied organs were then sucked out via an incision in his abdomen, an incision caused by teeth. The detectives report to Renard, telling him that they’re tracing the missing Rolex. There doesn’t seem to be any motive for the murder. Officer Franco reports that they got a hit on the severed finger’s print, and that it turned up at a murder in Phoenix five years ago. According to the files, that murder took place the same way that Ryan’s did, and the victim was an engaged man last seen at his wedding party. A wedding ring worth $10,000 was taken, and the tox report indicates that the acid contained enzymes found in spider venom. Renard tells them to check for more matches, and Nick tells Hank that he’ll check on the venom.
That night, Nick goes to his aunt’s trailer and checks her journals, and finds an entry concerning spinnetods.
At her home, Lena puts on a blonde wig and braces herself to go out and find another victim. She soon picks up a man, goes to his apartment, and kills him like she did Ryan.
Nick goes to see one of his neighbors, John Oblinger. As soon as John sees him, he tries to lock the door and run, but Nick easily catches up to him. He demands to know why John, an eisbiber, is watching his house along with his buddies. John tells him the same thing that Eddie did, and his brother Bud, Nick’s former refrigerator repairman, comes in. Bud admits that he started things but only because his fellow eisbiber wouldn’t believe him. Nick assures them that he isn’t going to kill anyone unless they threaten him or his girlfriend, and Bud assures Nick that he would never do that. The officer tells them to make sure that everyone they told gets the message.
A maid checks on Anton’s room and finds him dead, while Lena slips out unseen. However, when Nick and Hank are called in and check the security footage, they spot Lena and figure that she’s the same woman from the art gallery despite the blonde hair. Renard tells them that he’s checked with the police in Phoenix and confirmed there were two more murders five years ago at the same time as the first one. There were also five murders in Albuquerque five years before that. Hank and Nick figure that the killer is following a ritual, and must claim one more victim.
Lena drives to a park and looks for young virile men. She flirts with a man who comes over, but it quickly becomes clear that it’s her husband, Robert, and her daughter Sally is playing soccer in the park.
That night, Nick comes to see Eddie and ask him about spinnetods. Eddie admits that he’s not a spider fan and that the spinnetods are death-spiders, the black widows of the creature community. He doesn’t know much about them but suggests that Nick speak to Charlotte, a retired spinnetod.
Lena is at home making supper for Robert and Sally. She regrets missing them the other night but has something for Robert: a gold Rolex watch. Once Sally goes to do her homework, Lena tells him that the watch is for special occasions and that she loves him.
Eddie takes Nick to a home where creatures have gone to retire and introduces him to Charlotte. The woman confirms from Nick’s description that the killer is a spinnetod, and that she has to kill three young men every five years, over a period of nine days. If a spinnetod doesn’t kill, she ages rapidly. Charlotte, despite the fact that she appears in her 70s, is actually 26 years ago. The former spinnetod also tells Nick that they are drawn to shiny objects, accounting for the theft of the gold Role, and that she avoids such objects so she won’t be tempted. However, she half-jokingly admits that Nick and Eddie look appetizing and they quickly leave.
Nick goes back to the station and Hank tells him that they got a hit on the serial number of the Rolex at a middle school. The officers go there and meet with the principal, who explains that one of the students, Ben, who traded it in return for their mountain bike. Ben says that he got it from Sally. They call Sally in and she finally admits that she took it from her father. They arrest Robert and Nick confirms that Lena is a spinnetod. Hank points out that she has a bandage on her finger and they ask her how she hurt it. Lena claims that she cut it while making supper but shows them the finger and it’s intact.
Back at the station, the officers interrogate Robert, who claims that he got the ring at a swap meet. They point out how unlikely that is and Hank says that they know Lena isn’t the killer. Robert insists that he doesn’t know anything and Nick goes to meet with Renard, who warns that they can’t connect Robert to the murders. Nick disagrees, insisting that Lena is involved.
Lena goes out for the night, leaving her daughter with a babysitter, Cindy.
Nick checks the lab reports and confirms that Lena’s fingerprint matches the one on the severed finger. He goes in to confront Robert and tells him that he knows Lena is a spinnetod. Robert reveals that he’s a spinnetod as well, and realizes that Nick is a Grimm. He warns that he can’t stop Lena from killing for the third time, and that he doesn’t know where Lena goes when she kills. When Nick wonders why he’s still alive, Robert explains that he met his future wife in high school and they had a natural chemistry. She lets him live because she knows there’s no life for either one of them without the other.
Lena is at home taking a shower and looks in the mirror, realizing that she’s started to age.
Nick and Hank take a squad to the Marcinko home and search the place. Nick finds discarded human skin, while, an officer reports that they have a report from the harbor patrol that Lena’s car has been spotted at the marina. Meanwhile, Lena has manipulated an attractive young man, Aaron, into picking her up and taking her to his boat. When they hear something moving on deck, Lena asks Aaron to check it out. He does and Hank gets him off the boat. Meanwhile, Nick searches the boat and realizes that Lena has slipped out via a hatch. She attacks him in her spinnetod form and Nick manages to shoot her in the shoulder. Lena flees to another boat and Nick goes after her, and manages to knock her into a net.
Later, Nick and Hank pick up Sally to take her to her grandmother. They avoid telling her what happened to Lena and Robert. As Nick talks to the girl, he sees her transform into a spinnetod and realizes that it’s not over.
Lena sits in a jail cell and begins aging.