Kelly and Scott are eating at a Chinese restaurant in Hong Kong and waiting for their contact to meet them. Kelly is busy eating while Scott worries that their contact is an hour late. Mobster Danny Preston and his two bodyguards, Sam and Genius, come in and Danny immediately starts harassing the staff. While he orders a drink, a bus boy sets a plate with a loaf of bread on a nearby bus card. Once he takes off, another bus boy picks it up and tells the maitre d' that it's ticking. Scott overhears the exchange, garbs the bomb, and throws it out the window just in time as it explodes.
As the patrons clear out, the agents talk to the second bus boy, who admits that he doesn't know who left the bomb. They figure that the bomb wasn't meant for them since they haven't even got an assignment left. Meanwhile, Danny demands another drink from a waiter and has his bodyguard Sam grab the man. Scott finally has enough and stops Sam, who throws a punch at him. Kelly and Genius leap into the fight and are soon tearing up what's left of the restaurant.
The next morning posts bail for himself and his bodyguards. Scott and Kelly are stuck in a cell, but the sergeant comes in and tells them that Kelly's Aunt Helen has posted bail... and he doesn't have an aunt. The older woman snaps at them as she signs their bail papers and dismisses Scott as just as bad as her nephew. Outside, Helen gets them into her car and tells them that she's their contact and was detained until after they were arrested. She reminds them to keep a low profile and avoid brawls, and then drives off.
The agent takes Scott and Kelly to a makeshift clinic where Dr. Moran is working with the local children. They have a bone disease with a high mortality rate and black market drug-runners are cutting penicillin with ariomyacin to increase their profits. While Scott tries to cheer up one ailing boy, Helen explains that the U.S. supplies most of the antibiotics. The influx of contaminated drugs is ruining the country's image and she's there to make sure that American interests. A Senate committee is sending a representative to Hong Kong in a week to extradite a witness who can testify against the black marketeers, and the agents are ordered to protect him.
Back at the agents' hotel room, Helen refuses to sit down unless the door is open as a matter of propriety. She then demands a shot of bourbon and reaches into her blouse... and removes the pistol she's been carrying. After finishing off the bourbon, Helen tells the partners that the witness is Danny Preston and they have to protect him no matter what.
Once Helen leaves, Scott angrily goes on about Danny and considers letting him die. Scott waits it out until the phone rings, and the front desk notifies them that Danny is at the bar. The agents go down and find Danny eying the waitresses. Sam orders them off and Kelly punches him in the gut. They then explain they're there to protect Danny, which is news to him. He refuses to testify until Kelly reminds him that he'll have to testify in return for immunity or the government will put him away. When they explain that an assassin is after him, Danny doesn't believe it and dismisses the bomb as a coincidence. Disgusted, Danny and his bodyguards leave and the agents follow.
As Kelly and Scott wait outside Danny's hotel room, Sam suggests to his boss that they should take the government's offer of protection. Danny tells his bodyguard to leave the thinking to him.
The next morning, Danny and the others meet a tour guide, Kim, in the lobby. The mobster tells the guide to ignore Kelly and Scott and find them a decent restaurant for breakfast. Danny and his men drive off and the agents follow in a cab. At the restaurant, Danny flirts with the hostess, who gets the agents a table close to Danny. Kim offers to get some American food but instead meets with his accomplice, Wong, and tells him not to miss.
As Kelly and Scott order, Wong aims at Danny through the potted plants. Scott notices him and pushes Danny out of the way, and the bullet hits Genius instead, killing him. Wong gets away and Lt. How arrives with his officers to secure the crime scene. He's unimpressed with Danny's numerous complaints and orders them to stay in the city. How assures them that he'll keep them apprised of his investigation once he gathers more information.
Back at the hotel, the agents insist on going into Danny 's room, while the mobster tells Kim to stand by. He then switches his tune, telling the agents that he appreciates what they're doing. He offers to let them run up a bill on his tab and then tells Kim to find them a place to party. Kelly explains that he'll kneecap Danny if he tries to leave and Scott suggests that his partner wire Washington and expedite matters. Once Kelly leaves, Danny decides that he needs to hire a temp secretary and Kim assures him that he can find just the woman for him.
Later, Kelly checks at the front desk for a response to his wire and sees Kim bringing in a local woman, Nancy. Kelly draws her aside and suggests that she'd be better off refusing the job. Nancy assures him that she can do whatever it takes in return for the amount of money involved but thanks Kelly for his concern. As Kim takes Nancy up to Danny's room, Kelly spots Wong outside working on Danny's car. He chases the killer but loses him in the crowded streets.
Danny orders in room service and tells Sam to buy Nancy a fur coat. Kelly arrives and suggests that they call the police, but Danny figures that none of the mobsters he knows would both with something so amateurish as a car bomb. He sends Sam to disarm the bomb and then get the fur coat, saying that the bodyguard has defused plenty of bombs. Everyone watches from the window as Sam removes the bomb, waves... and then goes up in smoke.
Lt. How shows up to investigate the murder and tells Kelly that they captured Wong based on the agent's description. They recovered the gun and How assures them that ballistics will tie it to Genius' murder. Danny demands that they let him leave the city and tries to bribe How, who refuses and tells him that he's under orders to keep Danny in Hong Kong until the government man arrives to extradite him. Once the lieutenant leaves, Scott tells Danny that the government has sped things up and their man will arrive in the morning to take him to Washington. When Danny gets nervous, Kim reassures him, saying that they have Wong and he probably planted the bomb in the bread. He realizes that he's said too much and makes a run for it but the agents easily subdue him. Scott turns him over to How and Danny figures that he's in the clear since the mob always sends a finger man and a killer.
When Scott comes back, Danny sits with Nancy and thanks the agents for their help, and then tells them to get lost. The agents refuse to leave in case there's more trouble and the mobster tells them to wait outside. Kelly asks Nancy if that's what she wants and she tells him again that she'll do what she has to. A disgusted Kelly leaves with Scott and they go to their room. However, Scott still thinks something is wrong. Kelly says that everything is fine... until they realize that they never checked on Nancy, and Kim was the one who brought her in. When they go to Danny's room, they discover that Danny and Nancy are both gone. They go to the police station to interrogate Kim, who is initially defiant until they threaten to leak that he squealed on his bosses. Kim quickly caves and gives them Nancy's address.
When the agents break into Nancy's apartment, they interrupt Nancy making supper. Danny draws a gun on them and says that Nancy has promised him a place where they can go away and avoid everyone the mob and the Senate committee. Kelly disarms Danny and then asks Nancy how she was going to kill the mobster. He quickly realizes that the soup she is making is poisoned and demands that she take a sip if she thinks it's harmless. Nancy snaps and goes for her purse, only to discover that Scott has already taken her gun out. Danny tries to choke her but Kelly slaps him away. Nancy angrily tells Danny that he deserves to die for all the people he's killed, and that even though he's worthless, the price on his head is enough to get her out of poverty.
Later, Helen calls the agents to bail her out. When they get there, Helen explains that she ended up taking Danny to the airport. He kept opening his mouth and she finally closed it for him with a right hook. The senior agent sheepishly admits that she loved hitting him and the agents bail her out and take her to dinner to celebrate.