St. John and Mike are flying Airwolf when they see a woman named Sandra fall off her bike and nearly go over a cliff. They land to help her and take her to a nearby nun retreat where she recovers.
The next day, St. John test flies a fighter jet called the Viper for Conklin Aerotech, with Conklin, the owner, and his associate Jenkins watching on the ground, and Mike and Jo observing from Airwolf. The jet malfunctions, and St. John is unable to eject. Mike uses the laser to knock the hatch off so St. John can eject. Once he's out, the jet crashes into a mountain.
Angry about nearly getting killed, St. John confronts Jenkins with the burnt out motherboard he pulled out of the instrument panel before he ejected and demands to see the schematics on the aircraft. That evening, St. John finds that the materials used to build the Viper were substandard. He takes the disk containing the schematic with him. When he gets into a car that Jenkins loaned him, he's attacked by a man in the back seat. Jenkins comes out and shoots at them both, and the car suddenly explodes.
The rest of the crew arrives on the scene, and knowing St. John can't be dead, they question Jenkins. He maintains his innocence in the matter, and feeds them a phony story. Mike finds the disk St. John had and pockets it. As Sandra is leaving the retreat, an injured St. John stumbles into her and passes out.
The following day, Conklin talks to Jenkins and another man named Yarmy during a limo ride, and with St. John being the only other person who knows about the Viper's flaws, Conklin wants him dead. At the lair, Jason and Mike try to analyze the disk. Jo is upset after hanging up with the coroner's office, told that St. John's dental records were lost. Jason realizes that it's not a coincidence, and that it's a setup.
St. John wakes up at the retreat, patched up by Sandra, and she offers to call his friends for him. To protect her, St. John refuses before he passes out again. Sandra finds Jo's business card in his pocket and goes to a phone booth at the base of the mountain. As she leaves a message for Jo at the hangar, Jenkins and Yarmy trace the call in a car nearby.
In the lair, they run the tape from the answering machine, and Mike recognizes it as Sandra's. At the retreat, St. John is on his feet, and Sandra walks him to the phone booth, with a detour to a friend's home to check on the condition of her pregnancy. Jenkins and Yarmy stop at the bar where Sandra made her call and Yarmy purposely injures Jenkins's hand. The owner of the bar directs them to the retreat to treat it. Jason and Mike match up Sandra's answer machine message to the voice extracted from Airwolf's black box to confirm that it's her, and take off from the lair.
At the retreat, Yarmy threatens to kill the nuns unless they tell him where Sandra is. Jo figures out that the schematic on the disk was faulty, while Mike and Jason try to triangulate where St. John could be located in Airwolf. St. John and Sandra get to know each other, and she expresses the desire to become a doctor. St. John encourages her to follow her dream, just before they have to prepare for delivering the woman's baby. Mike and Jason get information from Jo about Conklin's scheme in deliberately using inferior materials to build the Viper and pocketing the difference; he's arrested by Company agents.
Yarmy goes back to the bar, where the owner tells him where St. John and Sandra are rumored to be. Meanwhile, the nuns knock Jenkins unconscious and take his gun, just as Mike and Jason arrive. At the woman's home, Yarmy arrives there, and St. John runs to lead him away. He runs to a barn with Yarmy shooting at him.
Inside the barn, St. John, who was covered in hay, jumps Yarmy from behind and they fight. Yarmy regains his composure, and is about to shoot until Airwolf arrives outside. Mike scares him away with chain guns, but he continues shooting at them and St. John as he hides near some barrels. With his visor down, Mike fires a missile at Yarmy, killing him and igniting all the barrels. Now safe, Mike and Jason take off as St. John and Sandra embrace.
At Santini Air, the crew reads the newspaper report on Conklin's indictment when Sandra comes to see St. John. She thanks him for restoring her confidence in pursuing her medical career, and gives him a goodbye kiss.