Stephanie is infuriated to learn that her boss/cousin, Vinnie, has hired her arch-rival Joyce Barnhardt as another bounty hunter. Vinnie tells her to "be professional" and focus on tracking down her latest FTA: Maxine Nowicki, a waitress accused of stealing her ex-boyfriend's car. Stephanie interviews the boyfriend, Eddie Kuntz, who doesn't know exactly where Maxine is, but she is still in the Trenton area - she has been leaving him taunting messages in code. Eddie mentions that Maxine has some embarrassing love letters he once wrote to her, and hires Stephanie for an extra $1,000 to track Maxine down.
Stephanie knows nothing about codes, but one of her neighbors mentions that her nephew, Salvatore Sweet, has a knack for such things. "Sally" is an aspiring rock musician who made his big breakthrough performing in drag. Interviewing Maxine's mother and friend Margie, Stephanie gets suspicious; someone else has been visiting them and demanding Maxine's whereabouts, going so far as to scalp Mrs. Nowicki and cut off one of Margie's fingers.
With Sally's help, Stephanie decodes the message, which leads her to the second, and third, and so on. Maxine's trail takes Stephanie and her hangers-on - Sally, former-prostitute-turned-backup Lula, and even Stephanie's Grandma Mazur - all over Trenton, to Point Pleasant, and even to Atlantic City. Stephanie encounters Maxine several times, but never manages to capture her.
Alarmingly, someone is stalking Stephanie, leaving threatening notes warning her to stay away from the stalker's boyfriend. Stephanie at first suspects vice cop Joe Morelli's old flame from high school, Terry Gilman, now a "facilitator" for her Mafia uncle Vito, and still carrying a torch for Morelli. When the stalker throws a firebomb through Stephanie's bedroom window, Stephanie is thankfully not home, but her apartment is almost entirely destroyed. In fright, she takes her hamster, Rex, and goes to stay with Morelli at his house. After a couple of false starts, she and Morelli finally resume their intimate relationship.
The stalker is discovered to be Sally Sweet's roommate, "Sugar", who was madly in love with Sally and convinced that his work for Stephanie was taking him away. With Sally's help, Stephanie and Morelli apprehend him at a nightclub.
When Eddie Kuntz disappears, Stephanie goes to his home, which he shares with his Uncle Leo and Aunt Betty. They appear unconcerned and refuse to answer any questions. One of Eddie's friends confides to Stephanie that Eddie passed him a counterfeit $20 bill, and Morelli admits that he has been working with the U.S. Treasury, monitoring a suspected counterfeiter in the area.
Stephanie goes snooping through Leo and Betty's basement, and finds a corpse wrapped in a garbage bag. Leo and Betty catch her and are about to kill her, when Lula distracts them with a gunshot through the window, allowing Stephanie to run and call for help. At the same time the police arrive to arrest Betty and Leo, Eddie Kuntz appears, having been kidnapped by Maxine and released after being tattooed with derogatory slogans.
A tip from Eddie's friend sends Stephanie and Lula to the airport, intercepting Maxine before she can leave the country. Joyce Barnhardt actually makes the apprehension first, but Stephanie and Lula, deciding they have earned the "collar", tase Joyce and leave her unconscious behind the wheel of her car. Mrs. Nowicki and Margie are also waiting at the airport, but Stephanie lets them go, since she has no authority to detain them.
Morelli reports that the investigation has turned out very well for the police: Leo is a retired enforcer for the mob in Detroit; twenty years ago, he stole a set of well-made counterfeiting plates and later decided to set up business in Trenton, washing the money through a dry cleaner's owned by another ex-Mafioso. Eddie helped with the counterfeiting, and couldn't resist bragging to Maxine about what a "big shot" he was. Maxine was once in love with Eddie, but he was abusive and unfaithful, and she planned the perfect revenge: after she was bailed out of jail for stealing his car, she pretended to make up with Eddie, persuaded him to show her the plates, then stole them.
The coded messages were a game to torment Eddie, who was desperate to get the plates back, but Maxine did not anticipate that Leo would go hunting for her himself, including mutilating her mother and Margie. He also killed his partner, the dry cleaner (the body Stephanie found in his basement).
Eventually, Maxine demanded $1 million in genuine money in exchange for the plates, and Leo complied. Maxine was planning to leave the country with her mother and Margie when Stephanie caught up with her. Stephanie and Morelli's sympathies are firmly with Maxine, and Morelli adds that no additional charges will likely be pressed against Maxine - there is no evidence of the blackmail, and Eddie is too humiliated to prosecute her for kidnapping - so Maxine will likely serve a short jail sentence for the original auto theft charge, and then be free to join Mrs. Nowicki and Margie and enjoy her million dollars.
Morelli invites Stephanie for a celebratory ride on his Ducati motorcycle. Stephanie, afraid of being relegated to the "helpless female" role in their burgeoning relationship, demands that he make the ultimate concession and let her drive. Morelli concedes, but says she will owe him later.