Jesse Colton and his dog Frog are looking for Frank Colton and MacGyver. As Jesse moves in to check a parked truck, a counterfeiter named Egan emerges from the building behind him and draws a gun. Jesse turns but the man shoots him twice in the chest. After the man drives away, Frog walks over to his master and nudges Jesse awake. Jesse pries the bullets out of his bulletproof vest and goes after Egan. The counterfeiter is picking up his partner and Jesse runs up behind them, leaps into the bed of the truck, smashes open the back window of the truck, and shoots out the dashboard.
Frog goes exploring and finds MacGyver and Frank tied up in the basement of the building, waiting for a bomb to explode. MacGyver spots a bottle of sulfuric acid on a nearby table. When Frank starts sneezing, he realizes that Frog must be nearby. They call the dog in and try to get him to bring them the bottle. With time running out, Frog refuses to cooperate.
As Jesse demands to know where his brother and MacGyver are, Frog finally knocks the bottle onto the floor and then carries it over. MacGyver sets up a board on a roller and Frog finally drops the bottle on one end. MacGyver kicks the other, catches the bottle, and uses the acid to burn through his ropes. The two men get free and run outside with seconds to spare as the bomb goes off behind them.
Later, Frank and Jesse go to Mama Colton's house. She tells them that MacGyver won't be able to make it over because he's hiding out in the mountains to avoid the news reporters. Billy is there and going over his college application. Chief Inspector Johnny Denmark stops by and wants to hire Frank and Jesse. He admits that they're the best in the business and needs them to find a girl named Medusa. She was the girlfriend of a dead Chinese godfather killed off by Chi, who wants to take control of the Chinese Mafia. Chi has bribed the Chinatown police to look the other way so he needs Frank and Jesse.
The brothers go to the restaurant and talk to the owner. She claims she can't remember. Two of the local police, Danko and Quilla, come in and pat down Jesse. They find his fake police ID and when he fights back, they toss him out. When Frank comes to his defense, Quilla draws a gun and Frank backs down. As the brothers leave, the owner calls down to Frank and tosses him a piece of paper with Medusa's real name, Patricia Fielding. They have Mama Colton check the name and determine Patricia is the daughter of G. Irwin Fielding and his wife Loretta Wu. G. Irwin is a former saving & loans owner who was busted for ripping off his customers. Loretta was a former fashion model. Mama Colton eventually gives them the address and has confirmed that the Fieldings are having lunch together at the private yacht club on the docks. Once she hangs up, Billy asks Mama Colton if he can avoid going to college. She tells him to get to registration so he can get a college education. Once she leaves, the room, Billy looks up the yacht club address and figures he can prove he's ready to join his brothers.
Loretta arrives at the club and finds Patricia outside. Patricia goes to talk to her. Frank and Jesse are watching and see them together as they go inside, and figure they can wrap up the case. As they go in, two of Chi's men report to their boss that the Coltons have found Patricia. He tells them to kill them all, the girl first. Meanwhile, Billy pulls up with Frog and notices the two men getting guns out of the trunk of their car. Billy gets his brother's shotgun out of their van and goes inside.
Patricia tries to get through to her unsympathetic father and explains that she witnessed a gangland killing and Chi wants her dead. She needs his help to get away but he refuses to assist her. Frank and Jesse come in and offer to help her. Outside, Frog finds one of the killers and attacks him just as he fires, and his shot goes wild. Frank goes after the man and knocks him out. The other man runs inside and opens fire just as Billy arrives. Billy tosses Jesse his gun so he can return fire. As they exchange shots, Patricia runs outside and escapes in a boat. Jesse finally shoots down a chandelier on top of the killer and knocks him out.
Later, Loretta calls the Coltons and tells them where they can find Patricia. She meets them at the address and reveals that Patricia is hiding with Loretta's friends at a hair salon. As they go in, Jesse notices Danko and Quilla in the reflection of a window. They get Patricia out but soon realize that the crooked cops are on their trail. Frank calls home and talks to Denmark, who is waiting to hear from them. Denmark tells them to go to a boatyard where they can meet his assistant Charles. He then calls... Chi and tells him where he can find Frank, Jesse, and Patricia. However, once Denmark has left, Billy recalls the number that Denmark dialed and tells Mama Colton that Frank wanted to her to track the call just in case.
At the boatyard, Jesse realizes that Danko and Quilla are so incompetent that Chi wouldn't hire them. He figures that someone else must have put Chi onto them and figures Denmark is involved. However, Chi and his men arrive before they can do anything about it.
Mama Colton's source at the phone company confirms that Denmark called Chi. Billy has no choice but to go after his brothers. Once he leaves, Danko and Quilla arrive and say they want to question Frank and Jesse. When Mama Colton finds out they attacked Jesse, she tells them it's time for a meaningful conversation.
Chi's men string Frank and Jesse up and then bring out the immigrant workers that Chi is smuggling into the country. One of the men explains that Jesse and Frank will serve as examples in case they try to escape without paying, and then shoots the two brothers dead. However, once everyone has left, Frank and Jesse stop playing dead. Thanks to their bulletproof vests, they're okay. However, a guard is nearby and they can't move or get down. Billy and Frog arrive and Billy sends the dog on ahead. Frank starts to sneeze and realizes that Frog is nearby. The dog goes over to the guard and Jesse calls Frog over and then has him bark. Billy realizes what's going on and watches as the guard goes over to investigate. Jesse and Frank free themselves and drop on the man, knocking him out.
Billy goes into the warehouse and finds the immigrant workers preparing small stuffed lizards for drug smuggling. He sees Frank and Jesse outside and then disguises himself as a worker and slips in with the others. One of the guards realizes something is going on and takes Billy away to the office where Denmark is meeting with Chi. Frank and Jesse sneak in and spot Billy being taken away, and Frank gets an idea. Denmark sees Billy and figures that his brothers know everything and Chi orders his men to get the payoff for Denmark and then kill Mama Colton. Frank and Jesse take to the rafters and get above the office. Meanwhile, Chi tells Denmark to kill Billy to seal their partnership. Denmark hesitates but realizes he has no choice. Mama Colton arrives with the police and the workers panic. As Denmark prepares to shoot Billy, Frank and Jesse drop in and shove Chi and Denmark out the third-story window into a garbage dumpster. Chi is knocked out in the fall, Jesse punches Denmark unconscious, and Billy captures the last man in the office before he can get his gun.
Mama Colton brings over Danko and Quilla and explains that they helped her. Billy calls down from above and assures them that he's fine. Mama Colton insists that Billy is going to college but her sons suggests that Billy might dabble part-time. They're surprised that she's finally letting go a bit and she admits she’s just doing it a little.
Later, MacGyver comes by as Jesse puts up a new sign saying they're expanding business as private investigators to improve their image and make up for the cash they lost because Denmark wasn't paying them after all. Billy and Frank arrive and Frank admits that his girlfriend decided not to go to Pismo Beach with him after all.