Michael Simmons, an employee with Vectrocon Systems, meets with an East German buyer. In return for three-quarters of a million dollars, Simmons is providing Vectrocon's top-secret navigation system commissioned by the government. However, once his buyer leaves, Simmons meets with his partner and girlfriend Linda and boasts of how he's sold them empty crates. He tells Linda to buy them tickets for Rio and meet him the next day.
MacGyver has taken his current payment from the Foundation in the form of a scrimmage game with the Squires. Pete comes by and MacGyver reminds him that he promised no assignments for at least a week. Pete agrees but then starts talking about the fact he's helping out the government by investigating a security leak at Vectrocon. They figure Simmons is responsible and want to bring him in. MacGyver knows all about it and agrees to help, and Pete directs him to a bar that Simmons owns.
Mob boss Charlie Banning is playing with his granddaughter when a limping man, Jimmy "the Eraser" Kendall, approaches him. Banning's two bodyguards try to intercept Jimmy, who easily knocks them out. Jimmy then embraces "Papa Chuck," who has been expecting him. Jimmy just finished serving a ten-year stretch in prison. Banning wants Jimmy to take care of one problem for him: the Mob is involved with Simmons, who conned them out of their money. Jimmy warns him that it's been ten years and he's not the same man. Banning hints he'll call in his markers unless Jimmy takes on the job. Jimmy agrees to take out Simmons.
MacGyver goes to Simmons' bar and help out the bartender with a sprayer valve. He gets her to talk about where to find Simmons while Jimmy comes in and seats himself at the bar. Jimmy strikes up a brief conversation and the bartender tells MacGyver that Simmons owns a car lot nearby. When MacGyver goes to check it out, Jimmy follows. MacGyver spots him and closes in, and Jimmy claims that Simmons is his long-lost son. He was supposed to meet Simmons, but his "son" ducked out on him and Jimmy figures he's in some kind of trouble. Convinced, MacGvyer agrees to call Jimmy at his hotel and bring him in once he locates Simmons.
Next, MacGyver breaks into Vectrocon to go through Simmons' desk. Pete isn't sure if someone else at the company is involved, so MacGyver sneaks in. He uses a power surge to get past the lock on Simmons' office and finds a photo of Simmons' girlfriend Linda on the desk, along with an address. He gets outside but two men ambush him. He manages to get away but a third one cuts him off. Jimmy arrives to take out the third man and get away with MacGyver. He admits he's been trailing MacGyver to make sure he doesn't get in over his head.
At MacGyver's place, Jimmy talks about how he was with the '47 Braves for two weeks but ended up as the team's bus driver. He admits that now he just wants to go somewhere and relax. MacGyver offers him his hospitality and Jimmy accepts. As they play table hockey, Jimmy figures that MacGyver used to dream of going pro as well.
The next day, MacGyver follows Linda from her address. Jimmy goes back to his hotel room and meets with the three men, who are working with him for Banning. The leader, Ralph, isn't happy that Jimmy's is in charge and taking the complicated route by using MacGyver. Jimmy tells him to follow his orders, stick to killing Simmons because he's the only contract they have, and let MacGyver do the hard work for them.
MacGyver follows Linda to Simmons' cheap office. Once she leaves, he rigs up the car phone to the security system. Once he's done, he calls Jimmy and tells him he's found Simmons. When Simmons and Linda get into the car, MacGyver dials them up. When Simmons puts the phone back down, the car locks seal the doors and the engine shuts down. MacGyver strolls over and tells Simmons to lift and put down the receiver again. Once the doors are unlocked, MacGyver hauls Simmons out and tells Linda to drive away. He tells Simmons they'll be going to FBI but first Simmons' father wants to see him. Simmons says that his father has been died for six years. Realizing something is wrong, MacGyver starts to get Simmons away but Jimmy and Ralph arrive and chase them.
MacGyver hustles Simmons into a nearby building and they go to the basement. They end up facing a locked door with no way to bar the door behind them. MacGyver rigs up a makeshift cannon by filling one pipe with flammable gas and putting a smaller pipe inside, then lighting a fuse and firing the pipe into the locked door. Once he and Simmons get through, they barricade the door behind them. Jimmy is waiting for them on the other side. He tells MacGyver to get out of the way and Simmons isn't worth protecting. MacGyver agrees that Simmons is scum but insists he be turned over to the authorities. He reminds Jimmy about how he just wanted to relax but Jimmy insists he has to go through with the contract. MacGyver refuses to back down and Jimmy finally tells him to take Simmons leave. They're unaware that Ralph is listening to the entire conversation. Simmons tries to run away and while MacGyver stops him, Jimmy slips away.
Ralph reports to Banning and offers to take care of Simmons. The Mob boss tells him to finish off Jimmy first then eliminate Simmons.
Pete visits MacGyver and tells him that Simmons confessed and they arrested his buyer. MacGyver has learned about Simmons' connection to Banning and the Mob. Sure that Banning will order a hit on Jimmy for his betrayal, MacGyver figures goes to find the hit man. Knowing of Jimmy's love for baseball, MacGyver finds him at a ballpark watching the kids play. Unfortunately, MacGyver figures out that Banning will figure out where Jimmy is just as easily. MacGyver sits down next to Jimmy, who admits there's no point in running. MacGyver reminds him of his love of baseball and suggests he go back to his former job as a trainer. Jimmy agrees but they're interrupted when Ralph and his men arrive.
MacGyver and Jimmy take a refuge on the upper floor of a nearby balloon-manufacturing factory. However, Jimmy warns that even if they escape this time, Banning will keep on sending killers. MacGyver gets an idea. He stretches out a sheet of Mylar vertically in front of a window, positions a studio light, and has Jimmy stand in front of a mirror. Ralph spots him from the alleyway below and opens fire. Jimmy goes down and Ralph runs upstairs to see Jimmy with his chest covered in blood. Before he can investigate further, MacGyver fakes a police siren using Mylar and a comb. The Mob killers quickly leave and Jimmy gets up, wiping off the red paint from his shirt.
Ralph tells Banning that he took care of Jimmy. A sorrowful Banning tells Ralph to make sure Jimmy gets a nice flower arrangement MacGyver and Pete are at Jimmy's (fake) funeral. MacGyver has taken his "payment" for bringing in Simmons by asking for another favor, and Pete assures him that they've set Jimmy up with a new identity in Florida. MacGyver figures that his friend will be happy with the job he found him.
In Florida, Jimmy is working as team manager for a minor league team. He assures his new team that for two weeks, the Braves couldn't go anywhere without him.