A cat burglar breaks into a luxurious manor. At home, Sledge Hammer receives a call from his old contact, Kurt Kruggle. Kruggle has information on the cat burglar who shot a cop, but doesn't want to sell his info over the phone. He arranges a meeting with Hammer at a bowling alley and Hammer goes there with Doreau. Kruggle rolls them instructions in the finger hole of a bowling ball, telling them to roll his payment down and he'll send the information back. Hammer rolls the ball and forgets to roll it in the gutter, knocking down Kruggle. Kruggle rolls him back the info but Hammer gets his finger stuck in a woman's bowling ball.
Back at the station, Norman Blates tries to get Hammer's finger out of the hole, while Commissioner Holbestam arrives to discuss the cat burglar robberies with Trunk. The Commissioner's wife knows some of the victims personally and wants the crimes solved. Holbestam tries to shake hands with Hammer and Doreau covers, but ends up revealing what happened. He tells Hammer that he expects results. Blates returns with margarine and they finally get the instructions. Kruggle informed them that the cat burglar is from England and has been hired to steal the specific victims. Hammer calls Scotland Yards and talks to Inspector Westcott. Due to the Inspector's thick Cockney accent, Hammer doesn't have much luck but does get the name Henry Hill. Hammer goes to talk to the wives of the victims and notices they all have the same hairdo. Hammer is less than sympathetic for their loss and orders them out, and Doreau asks where they got their hair styled. They direct Doreau to the Duke of Curl unisex hair salon and Sir Guy. Doreau checks into the robberies and determines they took place when the wives were getting their hair done.
Kruggle calls Hammer with more info on the cat burglar and wants Hammer to meet at an archery range. Kruggle raises his price and they meet at a bus stop. Kruggle picks up the money and leaves off the information, but a woman sits on it and Hammer is forced to try and get it off of her back. Doreau sends her on her way and find the name of the next victim, Felicia Waterhouse. The next day they stake out the house and see the burglar comes in, but Hammer almost gets run over by an ice cream truck. They go in and the cat burglar makes a run for it, but gets run over by the same ice cream truck and dies before he can say anything.
Hammer calls Westcott again and confirms the cat burglar was Henry Hill and he never worked alone. Doreau suggests that Hammer go undercover and get his hair done, figuring Sir Guy is involved. Hammer eventually agrees and drops Henry Hill's name, faking a Cockney accent. He suggests they carry on without him, hinting he's also a cat burglar. Sir Guy plays along and asks for his address to send some "free samples." Hammer goes back to his apartment and tries to get his hair unstyled. Sir Guy arrives and gets down to business: he admits he and Henry had a third man working with them, and they both want Hammer to break into the House of one of Guy's customers: the Commissioner's wife. Hammer promises to contact him in the morning then briefs Trunk and the Commissioner. They have Holbestam agree to loan them his wife's jewelry and Hammer will demand to turn them over in return for meeting with Guy's other man. Guy agrees but insists on going in with Hammer. Hammer has no choice but to agree. They receive the jewelry and Doreau points out Hammer has never broken into a house before and goes along as backup.
Hammer and Guy arrive at the house and Hammer goes in. It goes about as well as expected as Hammer snags a dog with his grappling hook and the pipe he climbs up on collapses. He destroys the rose fence climbing over it. He finally gets to the window and breaks the glass entirely. Climbing inside, Hammer finds a guard dog that grabs him. Commissioner Holbestam is waiting for him and Hammer realizes he was on the take: there was no way Holbestam could afford the house. Holbestam orders his dog to kill Hammer but Doreau arrives with a captive Sir Guy and the dog misses Hammer and goes out the window... and gets hit by the ice cream truck.