An attractive woman walks into Harry's shop and tells him that she's looking for a man. She introduces herself as Nikki Slovak and explains that her Aunt Freda believes in psychics and sent Nikki to hire Harry. Freda's lover, Donald Primko, stole $22,000 from her and she sent a toothpick that Primko used along, knowing that Harry would need it to magically find the man. Harry agrees to take on the case.
As Harry prepares his tracking crystal, Bob kibitzes and keeps asking Harry how attractive Nikki is. Harry finally gets tired of his badgering and orders Bob into his skull, and then heads off with the crystal. He follows the magic trail to an abandoned building... and a corpse, seared to the bone by hellfire. Harry calls in Chicago's Warden of the High Council, Morgan. Morgan is half-convinced that Harry is responsible given his past use of black magic. Harry insists that he's innocent and Morgan notices the brand of a flower on the corpse's palm.
Harry doesn't want to get involved and prepares to leave, but the police arrive and Morgan slips away. Murphy is less than thrilled to see Harry there and demands answers. He reluctantly gives her the name of his client but Murphy informs him that they checked traffic cameras and learned that the license plate of "Nikki Slovak" belonged to a Caryn Harris. They have an address and Harry insists on going with Murphy to check it out. When they get there, they discover that someone has turned the place upside down searching for something.
As Murphy checks out the bedroom, a saturnine man barges out of hiding, locks the bedroom door with a gesture, and knocks Harry down. The man catches Harry's wand and incinerates it with a touch, and then grabs Harry and demands to know where the "Chain" is. Harry has no idea what he's talking about, and the man leaps out the second-story window as Murphy shoots the lock out of the door. When she runs to the window seconds later, she discovers that there's no sign of the intruder. Meanwhile, Harry gets to his feet just as Caryn comes in. He grabs her before she can escape and Caryn insists that "he" will kill her.
At the station, Murphy interrogates Caryn while Sid taunts Harry about his possible involvement in the murder. Murphy comes out and Sid tells her that the fingerprints were burned off of the victim. There are also no signs of explosives or incendiaries. According to the coroner report, the victim was exposed to a high-temperature blast wave, as if he'd been exposed to the exhaust of a jet plane. Murphy admits that Caryn wouldn't say anything to her and Harry asks for ten minutes alone with her. Murphy reluctantly lets him even though she's sure he's holding something back.
When Harry goes into the interrogation room, Murphy watches on the surveillance camera but Harry shorts it out as Caryn asks if the High Council is after Primko's killer. She refuses to say how she knows about the High Council even though Harry assures her that he's working for her. He takes her hand in a gesture of comfort and Caryn insists that she didn't kill Primko. Harry mentions the chain and Caryn figures that he's working with the intruder, Sirota. Angry, she fires Harry, telling him that he must be willing to work with anyone, even the Devil himself.
When Harry goes out, he tells Murphy that Caryn fired him. Murphy plans to book Caryn for murder, and Harry ask her to make sure that Caryn is well-guarded in jail. Murphy has gone over the fingerprint reports from Caryn's apartment and discovered that they match that of a convicted thief, Matthew Jacobs. Since there were some on the headboard, Murphy figures that he and Caryn are lovers. Harry wonders if Matthew is the corpse, but tells Murphy that it's no longer his business.
Harry is lying and is soon in the morgue casting a spell to reveal the corpse true face. The corpse looks like a pale, bony human... a Hellion. Morgan appears and Harry explains that Sirota, a Hellion, was at Caryn's apartment. Harry wonders why a Hellion would have killed another Hellion, and the Warden reluctantly explains that Sirota is a powerful Hellion in Chicago. Primko was one of Sirota's recruits, and was transformed into a Hellion and then killed. That leaves Matthew, and Harry figures that he also works for Sirota. When Morgan says otherwise, Harry realizes that the Warden knows the Hellion. Morgan irritably admits that the High Council has occasional dealings with the other side and they have an "agreement." However, Harry refuses to let that get in the way when Caryn's life is in endanger and tells Morgan to take him to Sirota.
Morgan takes Harry to Sirota's office at Club C7 and the Hellion cheerfully greets Harry, apologizing for their early encounter. He tells Harry that he'll be glad to leave Caryn alone once he has his property, and Harry realizes that Sirota is looking for Matthew's Chain of Sin. The Chain binds a Hellion to its creator, and Morgan warns that Matthew is a major threat if Sirota doesn't control him. Sirota offers to hire Harry to bring him the Chain in return for Caryn's freedom. Harry reluctantly takes the deal because he doesn't have a choice, but storms out, angry at the High Council for compromising.
The police are moving Caryn in a transport van. Something forces the van over, attacks the drivers, and rips open the rear door.
Murphy soon hears about the attack and calls Harry. She figures that he's responsible but he tells her that Matthew is the guilty party. When he avoids giving her details, Murphy hangs up, disgusted that Harry is still holding back on her. Bob advises Harry to let it go for once, and Harry concedes that his friend is right... and has no intention of dropping it. When Bob wonders how he plans to find Caryn, Harry reveals that he stole Caryn's ring early at the station house.
Harry soon tracks Caryn by the ring and ends up at an apartment. A ritual circle is laid out on the floor, but before Harry can check it out, Caryn comes in. She orders Harry out and he tries to explain that Matthew is a Hellion. Matthew comes in behind his girlfriend and accuses Harry of lying, and Harry warns him that Sirota will eventually find both of them. Matthew insists that he'll be free of Sirota once he destroys the Chain, and Harry realizes that Matthew doesn't have it. The wizard pulls Caryn away but she knocks him out from behind with a wine bottle.
By the time Harry wakes up, Matthew and Caryn have gone. He goes back to the shop and tells Bob what happened, and then traces a path from Matthew's apartment to where Primko died. Harry figures that Primko left the Chain somewhere along his route. Bob wonders what Harry will do with the Chain if he does find it, and Harry reminds his friend of his deal with Sirota. The spirit points out that Matthew could have killed Harry when the wizard was defenseless, and Harry admits that has him puzzled as well. As he checks the map, Harry spots a cathedral, St. Margaret's of the Roses, that was along Primko's route and has the same flower symbol that was on Primko's palm.
The next morning, Harry goes to St. Margaret's and discovers that the handle of the main door has the flower symbol on it. When Primko, a Hellion, touched the handle, the holy forces branded the mark into his hand. Inside, Harry talks to Sister Beatrice and claims that he's Primko's brother, and that Matthew had a fight with their mother. Beatrice reveals that Primko hid the Chain in the church poor box and that she was holding it in case the donor changed their mind. She accepts Harry's story and turns the Chain over to give him. She comments on how when hate can turn to love, it can be miraculous, and Harry gets an idea.
Back at the shop, Bob suggests that Sirota could have at least paid Harry for his efforts. Harry realizes that his friend is hiding something and Bob says that it doesn't matter now. He did some research and learned that the ritual Matthew was preparing would have let him break the Chain and restore him to mortal status. Bob figures that it's too late now since Harry gave the Chain to Sirota. However, Harry takes it out of his pocket and explains that he had come to same conclusion and didn't want to let Sirota win.
Bob shows Harry how to use the Chain to summon its victim, and Harry summons Matthew into a containment circle. The wizard asks Matthew if he loves Caryn, and Matthew says that he does. Harry tells Matthew that he has to let Caryn go for her own safety, but Matthew explains that he already tried to push Caryn away. However, she refuses and the Hellion explains that while she was originally just another target to be corrupted, she saw what he was and forgave him. Not only did she forgive him for what he did, but for everything he would do. Bob says that there's only one thing that they can do, and Harry agrees, saying it's time to double-cross the villain
Harry arranges a meeting with Morgan in the park and tells the Warden what he's learned. He wants the High Council to protect the couple, but the Warden says that it's not any of their business. Harry insists that it's a win for the good guys, and finally begs Morgan to help.
That night, Matthew and Caryn come to the shop and Harry performs the transformation ritual following Bob's instructions. A blessing is required and the couple asks Harry to say a few words. He stutters through a brief blessing and then performs the ritual. The Chain shatters and Harry pulls Caryn out of the way as the black demonic essence shoots out of Matthew from every pore in his body.
Someone enters the front door and Bob, hearing the bell, says that it's his cue. Morgan and Sirota come in and Morgan tells Harry that he's saving him from himself. As the Warden slaps Harry to the floor, Sirota tells Matthew that he's no longer of use to him now that he's human. Harry pulls Caryn out of the way as the Hellspawn fries the now-human Matthew with a burst of soulfire. Morgan warns Sirota that the High Council won't be happy that he killed a human, but Sirota dismisses his complaint and leaves.
Once the Hellion is safely gone, Harry tells the sobbing Caryn that she can drop the act. Bob, disguised as Matthew, emerges from the floorboards where his skull is hidden, while Matthew comes in from the next room. As Morgan prepares to take the couple into hiding, Harry complains that Morgan hit him too hard. He thanks the Warden, who tells Harry not to mention it... to anyone, ever. After they leave, Bob says that Harry did a sweet thing and Harry goes to clean up.
Later, Harry brings Murphy hot chocolate and key lime pie, and gives his word that the missing couple won't be a problem anymore. She demands answers but Harry says that he can only tell her that he's not telling her. Murphy is less than happy but Harry tells her to relax and enjoy her pie.