At the Triad Nuclear Facility, Dr. Longfellow has a security guard let him into his office while two men in masks and full gear enter the facility and steal canisters of plutonium. They kill a guard and take off in a van.
At Santini Air, Mike and St. John disturb Jo by playing basketball. Afterwards, they all talk about Jo's father, Tony Santini. Jo paints him as a decent man, but somewhat of a scammer. When they hear an airplane flying overhead, they go outside and see him showboating. After landing, he and Jo have a happy reunion. During lunch, Jason calls Mike and St. John away to be briefed on the plutonium theft, leaving Jo and Tony to catch up.
After talking with Jason, Mike and St. John take off in Airwolf and go see Longfellow at Triad. He tells them that the thieves had an access card to the facility, but denies that it's an inside job. They view the video and see the van used in the heist.
After leaving in Airwolf, they pick up the van on the scanners and follow it. St. John fires a missile to send it off course, which kills the driver, but they fear the worst when it looks like the impact leaked some plutonium. Jo and Tony bring them radiation suits. On the flight in, there's brief tension between them, but it's resolved before they land.
Donning the radiation suits and a Geiger counter, St. John and Mike check out the van. They're confused to only find empty canisters inside. When they get back to Jo and Tony, the Geiger counter goes haywire near Tony. He reveals that he's received radiation treatments for cancer. Jo is upset that he kept it from her, and he's certain that after seeing a number of doctors, there's nothing that can be done.
Longfellow meets with one of the thieves, named Sullivan, who's holding Longfellow's family prisoner until all his demands have been met. He then flies off in his Gazelle chopper. In Airwolf, Mike reviews the video of the heist and discovers that Sullivan switched canisters with the empty ones they found earlier, faking the heist and making them realize that following the van was simply a goose chase. Jason contacts them and informs them that he's located Sullivan's team, who's trying to trade plutonium for weapons. Mike and St. John are upset to learn an added detail: they're Neo-Nazis.
At the hangar, Jo continues the conversation about Tony's cancer, and is upset when he won't open up. At Triad, St. John explains to Longfellow what they've learned about Sullivan's group. This further frightens Longfellow, as his family consists of an African-American wife and mixed-race daughter. St. John places a bug on Longfellow's phone, and when Sullivan calls, Jason, back in the lair, is able to trace it to a farmhouse a short distance away.
At the farmhouse, Sullivan and his man Sherman terrorize Longfellow's family at gunpoint with racist insults. He plans to start a new society with purebred Whites. Longfellow escapes his office after knocking a Company guard unconscious. At the hangar, Jo is trying to convince her father not to give up on treatments. Jason calls her away to help with the case, and Tony insists upon going with her.
At the lair, Tony blurts out that he worked reconnaissance during WWII, and Jason wants to utilize him, against Jo's reservations. St. John and Mike locate the farmhouse, and detect the real plutonium in a space below the barn. Down the road, Tony fakes a broken down truck to stop a load of guns going to the farmhouse. Jo and Jason come from behind the truck and force them to give up their van. Jo and Tony drive the van to the farmhouse pretending to drop the load off, and become Sullivan's prisoners. To top it off, Longfellow shows up. Jason stops him from going inside and ruining the plan.
Jo and Tony are thrown into the room where Longfellow's family is kept, but Sullivan comes back for Jo a moment later. They're gassing the place to set it afire, but want to take Jo with them. Outside, Jason and Longfellow sneak up and knock one of the men unconscious and throw him into his van. He tells Longfellow to hide out in the barn. Inside, Tony yells to get Sullivan's attention, and he shoots through the door.
Jason gives St. John the signal, and he fires a missile at the van. Upon hearing the explosion, Sullivan sends Sherman upstairs to check around. The distraction allows Jason to get inside, while at the same time, Tony kicks a hole in the door where the bullet holes were made. Jason and Sullivan have a standoff as he holds his gun to Jo's head, but it allows Tony and Longfellow's family to escape to the barn. Sullivan leaves with Jo, and outside, Tony is hiding in a shed when they run by. Tony attacks Sullivan to free Jo, but he shakes Tony and gets to his chopper. Meanwhile, Jason checks the rooms upstairs and one is locked, but he continues down the hall.
Sullivan goes airborne and St. John and Mike follow. Sullivan hides behind some trees and maneuvers behind Airwolf, shooting. Sherman quietly opens a door behind Jason's back, aiming his rifle, but Jason instinctively turns around and shoots him. Sullivan is flying his chopper towards the barn to crash it and release the plutonium, but St. John successfully fires a missile, stopping him in his tracks. Everyone is now safe. Jo feared her father would be killed when Sullivan fired into the room earlier, but he was saved by his cowboy belt buckle taking a bullet.
At the hangar, Mike and St. John are playing basketball, when Jo walks in, ready to go on a trip with Tony. He's agreed to resume his cancer treatments, and as a show of confidence, he shoots a basket with one hand and his eyes covered, and makes it in.