DI Gilks pounds on the door of Dirk’s apartment. Inside, Dirk finally wakes up, drinks a glass of wine, and checks his answering service. Meanwhile, when Gilks gets no answer he has his men break down the door. Fully dressed, Dirk leaps out of bed and runs down the fire escape, climbs down a ladder, and gets into Princess. It starts and Dirk manages to drive away.
Gilks goes to the office and Dirk isn’t there, but he catches Richard in. Janice is busy refusing to answer the broken phones until she gets paid. The DI confirms that they have no current clients and asks Richard for a list of former clients. Once Richard provides it, he asks Gilks what they have to do with Dirk, and the DI tells him that two of them are dead and their only connection is that Dirk worked for them. Once he leaves, Dirk emerges from a trunk and says that he’s being framed for murder.
As Dirk goes through his desk, Richard watches Gilks from the window and tells his partner that he needs to speak to the police. Dirk refuses and tries to find his passport so he can leave the country. Richard is surprised and disappointed that he’s abandoning the business. A woman comes in and Dirk recognizes her and starts to climb back in the trunk. When that doesn’t work, he hides his face behind a file folder. The woman, who identifies herself as Melinda Fulstone, says that what she can see of Dirk’s face looks familiar and asks for a closer look. He finally gives in but she doesn’t recognize him, but Gilks spots Dirk from below and comes up with his men. Dirk asks Melinda to accompany him for a brisk stroll on the roof to help think. When she agrees, he leads her out through a hidden ventilator shaft and Richard goes after them.
On the roof, Melinda explains that someone has been stalking her. Meanwhile, Gilks and his officers continue the pursuit until the trio gets to Princess and manages to get away. It breaks down shortly thereafter and Dirk starts flirting with Melinda, who admits that she was recently divorced when her husband went off with the pool cleaner. She also was in a car crash recently and hasn’t gotten out much, so she enjoyed the exercise. Dirk finally gets around to discussing his fee and she assures him that it’s her ex-husband Roger’s money.
The detective takes the case and puts her into a taxi, and Richard asks if he plans to solve Melinda’s problem before or after he leaves the country. Dirk assures him he can solve the case in a few seconds because he’s the stalker. One night she caught a glimpse of him outside but not enough to recognize him at the office, and she found his card at the local newsagent where Dirk went to take a break. He studied Melinda to see if her handwriting matched her predicted personality traits, because a former client gave him the forms that Melinda filled out after the car crash. As they sneak into Dirk’s flat, Dirk admits that he was planning on fleecing Melinda, but now that he’s met her in the flesh he finds her attractive. The detective then goes through his messy flat, looking for his passport and explaining that he doesn’t pay his cleaner, Elena, but she still comes by for two hours a day just to stalk him. Elena comes in and Dirk draws Richard to the side and explains that she puts a rug in a particular position every day. Richard pulls it aside and finds a hole, and Dirk explains that it’s there because of another dispute he had with his plumber.
As Richard finishes covering the hole back over, Gilks comes in with Dirk’s passport and takes him to the station. Dirk chooses to represent himself and Gilks explains that both victims apparently died of heart attacks. The coroner thought it was suspicious and found traces of a rare toxin. However, Gilks doesn’t think Dirk is competent enough to perform two such skilled murders. He’s been after him to take him into protective custody. Dirk resents the implication that he isn’t competent enough to commit two simple murders, and secretly pockets the photos of the victims. Gilks finally concurs and suggests that a ghost hitter might be involved, and advises Dirk to accept police protection. Dirk refuses and leaves.
When Dirk meets back up with Richard, he explain that a ghost hitter is a mob assassin who never meets his employer and always makes sure that it looks like natural causes. Dirk dismisses the stories as rumors but Richard realizes that he’s worried. As he decides to accept himself as a client, two men arrive and whisk the partners away in a van. The heavies finally tell Dirk that his cleaner Elena hired him and give him one day to pay or break his finger as a demonstration, and then drop the two men into the street.
Back at the office, Dirk pays Elena using Richard’s credit card while Richard notices an eviction notice. Dirk snatches it away and tries to find a cleaner. Richard suggests they solve the case first, but Dirk figures that everything will come together at the end. His partner isn’t convinced and suggests that they act like real detectives, and Dirk reluctantly admits that he’s right. When Richard jokingly asks if he’s framed anyone for murder, Dirk admits that he did, once, and the Ice Box Killer, Robbie Glover, got out of prison two months ago.
Dirk and Richard go to the library where Robbie now works, and Dirk explains that Robbie was the prime suspect in one of his cases 10 years ago. Post-it notes were going missing in an office and there was nothing on the security cameras. Dirk was so convinced that the watchman, Robbie was responsible, that he planted post-it notes in his office. It turned out that it was a clerical accident and no one stole the post-it notes, but the police searched Robbie’s flat and found his murdered brother’s corpse. While they’re talking, Robbie leaves his desk and turns off the lights. Fortunately, he just walks out and they follow him.
The partners watch as Robbie buys syringes and bleach, and Dirk figures he’s buying his murder weapons and sterilizer for the crime scenes. Robbie parks outside a graveyard and see him take some tools out of the boot of his car. He sees them and comes over, and Richard tries to claim that they’re dogging. Robbie is well aware that Dirk is there, and he insists that they come see what everything is for. They reluctantly go into the nearby church hall and Robbie explains that he and the other ex-convicts there are part of From Jail to Jesus, and are fixing up the hall. Richard tries to leave but Dirk decides to test Robbie’s knowledge of the Bible. When Robbie asks if he believes in anything, Dirk rattles off a list and laughs, and Robbie pities him for lacking a spiritual dimension to his life. The detective asks Robbie if he plans to murder again, and Robbie grabs his throat and admits that he still hates him. After a moment Dirk tells him to get off of him and walks out.
Outside, Dirk reveals that he stole Robbie’s keys and they search his car. However, he’s convinced that Robbie is innocent when he discovers how filthy his car is, and that his Js indicate he’s not a murderer. When Richard suggests that they let Robbie hire him so he'll be murdered like their other clients, they remember that they have a client, Melinda… and there’s a client-killer on the loose. The partners drive to her home and find Gilks waiting for them with a cup of tea. Melinda invites them in and Gilks suggests that the stalker she’s been telling him about is connected to the client-killer. Dirk asks for a loan of 20 pounds and insists that the stalker isn’t connected to the killer. When Gilks wonders why, Dirk rattles off an explanation and then asks Melinda out on a date. Undeterred, Gilks wants to pursue the stalker angle and has Melinda show him where in the gardens she saw the man.
While they’re alone, Richard asks why they’re still there and Dirk explains that they’re looking for the mystery stalker. Gilks confirms that the stalker entered the house and stole her receipts, and calls in a team to dust for prints. When he realizes that he didn’t wear gloves, Dirk runs over and examines the dresser where the receipts were. When Gilks pulls him away, Dirk insists that the stalker and the killer are two different people, and finally admits that he’s the stalker. He suggests they put the stalker business behind them and hope it doesn’t cast a cloud over their date on Friday.
Gilks locks Dirk up and Richard finally comes to see him. He complains that he’s been questioned as an accomplice and then tells Dirk that another client has been murdered. Richard assures his partner that Melinda is fine and that the police are moving her and the other clients to a safe house. He’s told Gilks about Robbie and the DI is bringing him in. Richard warns that if Gilks is the killer, then he and Dirk is responsible for the last death because he kept Robbie’s name from the police.
Later, Gilks releases Dirk and explains that Melinda has dropped the charges based on something that Richards said to her. As Dirk collects his personal belongings, he sees Robbie seated for questioning and the ex-con glares at him. Back at the office, Richard explains that he told Melinda the truth and that she was weirdly flattered. Dirk finally notices that his new cleaner has arrived and gives her his address. He then tells Richard that he’s going to overlook his behavior at the police station. A call comes in and Dirk takes it, and then informs Richard that the police are releasing Robbie due to lack of evidence. Richard, unconvinced, throws Dirk a receipt they found in Robbie’s car for a storage unit. When Dirk insists that Robbie isn’t the killer, Richard snaps at him and says that he’s tired of his antics while their clients are dying. Dirk agrees to check out the storage unit while Richard watches Robbie, but Richard warns that once they’ve found the killer, he’s done.
While Richard watches Robbie hand out syringes to drug addicts on the street, Dirk breaks into the storage unit. He finds a wall covered with newspaper clippings about himself, photos, syringes, and photographs of the three dead clients. Dirk calls and tells Richard that he was right, and Richard admits that he stopped following Robbie because Dirk said it was a dead end. Robbie enters the storage unit and tackles Dirk, choking him and insisting he isn’t going back to jail. Richard arrives just in time to knock Robbie out from behind.
Later, Dirk is sitting in his empty office, which has been stripped bare. Gilks comes in and is happy to point out that no one wants to hire Dirk because of the client-murders. He also points out that Richard isn’t there, and Dirk unconvincingly says that he’s taking some personal days. The DI informs Dirk that Robbie has been charged and the evidence is conclusive. Dirk follows him to his car and asks if it would have made a difference if he had told him about Robbie earlier, and Gilks says that more people would have lived.
Dirk goes to see Melinda and tries to kiss her. She backs away, lets him in, and explains that her husband has come back around because his boyfriend threw him out for looking at other women. Melinda has decided to give him another chance, and Dirk notices the note she was starting to write to him. He says that it’s not Melinda’s handwriting, and she insists that it is. Melinda broke her wrist in the car crash and it just recently healed back to normal, and her cleaner Marta has been doing all of her paperwork. Dirk asks what the cleaner’s traits are. He then realizes that he’s been stalking the wrong woman, wishes Melinda well, and immediately leaves.
Richard goes to Dirk’s flat and reminds Dirk that he called him. Dirk ushers him in and then goes back to his board of clues and notes, while saying that his cleaner is working out well. He explains that his subconscious won’t let him accept the case, and Richard says that he has to go. Dirk says that he needs him, and a touched Richard agrees to stay for now as a favor.
Dirk reviews the case and explains that they found the evidence too easily, and that his cases usually take a more circuitous route. He suggests that Robbie tried to strangle him because he saw the wall of evidence and assumed that Dirk planted evidence again. When Richard wonders why anyone would do that, Dirk figures that someone framed Robbie so the police would bring the other clients, including Melinda, out of hiding. When he remembers that Melinda won’t be coming over, Dirk tries to tell the new clearer that they won’t need the pot roast. He then admits that he was stalking Melinda by mistake, but realizes that the traits Melinda described that Marta had don’t match the handwriting either.
As Dirk tries to put everything together, the cleaner first arranges the pillows on the couch and then brings out two glasses of water for Richard and Dirk. As Richard starts to drink his water, Dirk realizes that the pillows on his couch are in the same arrangement as those on one of the victim’s couches. He knocks the glass out of Richard’s hand and then drops his own. The cleaner glares at him and speaks English for the first time, saying that he made a mess and she hates messes. She starts throwing knives at them and they run to the window. As the cleaner moves in for the kill, she steps onto the rug that Richard that Richard put down earlier... and goes right through the hole into the apartment below.
Later, Gilks and his team take away the injured cleaner. Dirk listens to the DI talking to the killer and confirms that she’s actually The Cleaner, wanted by the FBI and Interpol and with a sizable reward for her capture. He reluctantly admits that it’s their money, his and Richard’s, and that they could pay off their debts and reopen the office. Dirk admits that he couldn’t have solved the case without him, and then offers to tell him who the evil genius behind it all is. Richard agrees and Dirk explains that Janice inadvertently hired the killer by buying a cheap answering machine. Their clients left their names and addresses, which were forwarded to the assassin’s answering machine. Posing as a cleaner, the Cleaner killed them but never got paid, so she sent the heavies to get the money from Dirk. She then framed Robbie so the police would withdraw their protection and she could eliminate the remaining clients.
Gilks hears Dirk’s explanation and points out that his cheapness got three people killed. Richard responds by noting that thanks to Dirk’s cheapness, there was a hole in the floor that saved their lives and allowed them to capture the killer. The DI disgustedly says that Richard and Dirk deserve each other and walks away, and Dirk thanks Richard for supporting him. Richard says that he wishes that things had worked out with Melinda, but Dirk assures him that it’s okay and that he’s been hired to go after a con man with extreme body odor.