A woman makes a panicked call to 911, screaming that a man is in her house and he's going to kill her.
Lindsay and Jacobi show up at the house to find a man's body. Claire identifies him as a neighbor of the caller, Corinne Stevens. She also explains that the man was knocked over the head and then stabbed eighteen times. Lindsay notices a crystal rabbit near the body, which Claire says was smashed into his skull. She also realizes that the killer has kidnapped Corinne, who we see is being held captive in a house and screaming for help.
Corinne has been missing for ten hours. Lindsay catches Cindy up on the case: Corinne and her neighbor, Fred Osner, came home to find the killer in the house. Corinne ran, and Fred was killed. Corinne tried to hide in another room and made the 911 call there.
Lindsay and Jacobi talk to Corinne's husband, who was away at the time of her murder. Despite his anger problems, Richard Stevens denies murder and says that people saw him at the hotel where he was staying. Richard appears confused when Lindsay brings up the crystal rabbit, since he has never seen one before in his house. He also says that nobody had a grudge against her either.
Richard's alibi checks out, and Lindsay realizes through lack of fingerprints that the killer brought the crystal rabbit with him to the scene, and that he was trying to send a message to the cops. In the morgue, Claire tells Lindsay that Fred was kicked in the head post-mortem, and that hair fibers were found seemingly covered in blue paint. Lindsay confesses that she believes the Kiss Me Not Killer was responsible. She tells Claire that the crystal rabbit is part of his pattern of putting items from rituals near his victims, and that his pattern of only murdering women and sewing their mouths shut was spoilt by Fred Osner showing up.
The next morning, Pete wakes up in Lindsay's bed and tells her that he has noticed she seems distracted by work. Lindsay shows Pete her attic room, which is completely dedicated to the Kiss Me Not Killer. She tells him that she needs to find him in order to get him out of her life.
At work, Tom tells Lindsay that the blue fibers in Fred's hair were from the bottom of the Kiss Me Not's shoe. Jacobi shows up with information that it was specialty paint used in the restoration of old cars from the '50s. Lindsay and Jacobi go to the only dealer who has the paint in stock, a man named John Harris. He gives them a list of customers and employees, and a videotape showing him at the shop all night. Back at the office, Jacobi arrives with info about John Harris. His 15-year-old daughter disappeared 16 years ago and her remains weren't found until 2003. One of the cops working the case was Lindsay's father.
Lindsay visits her father, who remembers the case. His prime suspect was Harris's son Billy, who was only 12 years old at the time but "strange". Billy Harris works in his father's auto shop, and has been sick for the past three days. At the Harris house, Lindsay discovers a photograph of lilacs, a key in a box, and all the other ritualistic objects found near the Kiss Me Not victims. They all belonged to Rachel Harris before she was kidnapped. Billy Harris is the Kiss Me Not Killer.
John Harris says he doesn't know where his son is, and he was out of the city when a previous Kiss Me Not victim went missing, ruling John out as a suspect. However, DNA found on the duffel bag where Rachel Harris was dumped matches her father's, and the Club believe that he killed his daughter before claiming she ran away from home.
Lindsay gets a call from Billy Harris, who tells her that they must release his father in order to keep Corinne alive. A trace on the call fails. Lindsay is clearly shaken. At a coffee shop, Lindsay tells Claire that what happened was also a release. The Kiss Me Not had always been a "phantom", but now she knows his face and identity. They also talk about Pete, and Claire believes he loves her.
Cindy gets hold of notes made by Billy's former psychologist when he resided at a juvenile detention center. She says that her friend may lose his license for handing over the notes, but only if he doesn't get them back. Cindy shows The Club a picture Billy drew aged 12, a woman with her mouth sewed shut. Also in the book is an article written about one of the Kiss Me Not's victims, before she wound up dead. Lindsay believes that Billy witnessed his father murder his sister, and that the mouths being sewed shut represents silence, or a secret nobody can tell. John Harris may have also threatened his son. She also realizes the connection between the victims. Each victim has a relationship with an older man, including Corinne, who is married to somebody much older than her. Billy is re-enacting his sister's murder over and over again with different women who are involved with older men, just like she was emotionally involved with her father.
Billy calls again, telling Lindsay that she didn't listen to him earlier. Jacobi traces the call, just as Billy remarks that Lindsay has "a nice dog". The Kiss Me Not Killer is inside Lindsay's home. The cops race around to her house, where they discover Corinne Stevens dead on Lindsay's bed with her mouth sewn shut. Lindsay blames herself for Corinne's murder, but Claire tells her that Corinne was murdered hours ago, before Billy called her the first time round.
Billy calls Lindsay, angry that she took something away from him. In return, he has taken something away from her, and reads out her cellphone number. Lindsay reaches her phone, and discovers an IP address on the screen. Punching the address into her computer, a site comes up with a live webcam shot of her father being held captive. Billy tells her to bring him his father, in return for her's. She has five minutes to decide what to do. He tells her to meet him at a specific location in an hour.
The FBI are called in, and Lindsay suggests putting an explosive grenade in Billy's hand in order to stop him. But she needs to get five feet away from him in thirty seconds before it blows up. Lindsay and John Harris travel to the country cabin where Billy is holding Lindsay's father. Billy exits the cabin with a gun in his hand, demanding Lindsay put down the bag she is holding (which contains one of Rachel Harris's bears, which has a grenade inside). Billy loses his mind, blaming his father and telling him that he followed his demand to "never tell". Billy shoots his father dead, before turning the gun on Lindsay. She offers him the bag full of Rachel's things. He opens the bag, and says he doesn't want them.
Lindsay is forced into house where she sees her father alive and tied to a chair. The walls are covered in pictures of Rachel. Billy says that he could have saved her from their father, but couldn't. Lindsay tells Billy that what happened to Rachel wasn't his fault, and that with his father gone he doesn't need to keep the secret anymore. He makes Martin Boxer tell Lindsay that he hates her, but Marty ignores him. He tells Lindsay that he loves her with all his heart. Enraged, Billy shoots Marty, and Lindsay grapples with him, fighting him on the floor. Billy gets the upper hand and starts strangling Lindsay. Marty kicks the gun over to Lindsay, who kicks Billy off her and shoots him repeatedly in the chest. Lindsay runs over to her father, who is taken away in an ambulance. Lindsay promises to check on him at the hospital later in the night.
Lindsay rushes off to the airport to say goodbye to Pete. He says that he's delayed his flight, and couldn't leave without seeing her again. Lindsay says that with the nightmare of the Kiss Me Not over, she has finally learned that she wants to be happy, and that she loves him. Pete tells her that their relationship doesn't have to end, and that through cellphones and vacations, they could make it work. Lindsay says she would like that.
Lindsay meets up with The Club and catches them up on her new relationship. The girls gossip about the troubles of long-distance love, until Lindsay's cellphone rings. It's the hospital and she is clearly shocked. Claire, Cindy and Jill are all concerned. Lindsay turns to her friends, "It's my dad…"
The screen fades to black, and Women's Murder Club comes to a close.