Mike is in Laos trying to get past some Laotian guards to meet Colonel Curtis for a drug trade. Curtis was St. John's commanding officer in Vietnam, and gave his own troops heroin during the war. He set up shop after the war, being the only person growing and selling raw opium in the world.
Mike meets with him in a Laotian village and makes the trade. As Mike leaves, Curtis orders him killed. St. John, obsessed with nailing Curtis, covers Mike on his route in Airwolf. A jeep comes up shooting at Mike, and St. John gets turned around and fires at them, sending them off course. Mike and St. John meet later at a dock in Singapore, where St. John gives Mike fake ID and Mike gives St. John photos of Curtis. They split up, with Mike boarding a ship.
St. John checks in with Jason, making it clear that getting Curtis is personal. Mike's shipmate, an older, gray-haired man named Maxie, questions him about his visit to Singapore. Mike gets annoyed and goes out on the deck, and Maxie goes through his things. Out on deck, Mike signals a man in a dinghy with his flashlight, then grabs a duffle bag he had hidden in a rescue boat and prepares to leave the ship. Maxie, assuming he's smuggling, tries to stop him. Demanding a share of the profits, Maxie pulls a knife on Mike. Mike dodges him and Maxie goes overboard into the water. Mike catches the dinghy ashore, where he is shot – the man works for Curtis and sent his regards.
Mike survives the gunshot, as he was wearing a bulletproof vest. He later swaps out with St. John and pilots Airwolf in France, with Jo and St. John on the ground. He watches from a distance in whisper mode. Jo, acting as a drug chemist named Helene, walks into a warehouse with another woman, Giselle. Her purse contains a hidden camera and records the activity inside. They are met by a man named Felix, who immediately takes to Jo. Once in the lab, Giselle warns Jo about Felix, telling her to steer clear of him. She's had past experience with him, enduring his physical abuse. Felix later comes on to Jo and orders Giselle to leave so they can be alone.
Outside, St. John, with a fake facial scar and going by a mule named Ryan Murphy, arrives to the lab to pick up the product. When he goes into the lab, he catches Felix forcing himself onto Jo. When he interferes, Felix takes great offense to his presence and pulls a switchblade on him. He challenges St. John to a knife fight, with the victor winning Jo.
The fight goes down, and St. John overtakes Felix. St. John wins Jo, and Felix reluctantly accepts the loss with no hard feelings. With that out of the way, everyone packs dope into hidden crevices of several cars to make the delivery. As Jo leaves Giselle behind, they nonverbally acknowledge respect for each other and wishing each other well. The cars, St. John's included, convoy out of the warehouse, and Jo is taken to be picked up in Airwolf. Jason tells Mike and Jo that Interpol spotted Curtis in London, but his plane took off before they could move in.
St. John successfully makes it through a checkpoint and later customs to make his flight. Jason decides to join the crew in the field to back St. John up in New York, as three major buyers are meeting there for the drop off. Jason picks St. John up at the airport and hooks him up to a wire, and with bad street slang, go to the pickup point, which is disguised as a carnival. They're patted down inside, and St. John is shocked to hear that it's Curtis's operation.
At the risk of being recognized, St. John remains part of the mission, bent on taking Curtis down. A moment later, Curtis enters the room with some men. He almost recognizes St. John, but St. John is able to throw off suspicion. One of the major distributors shows up with the news that Felix just got busted in France, and other major players in key locations have also.
Curtis packs Jason's cash and tries to leave. Having what they need to bust Curtis, St. John willingly blows his cover, reveals his wire and tells Mike to shoot when Curtis comes out. Curtis pulls a gun and forces St. John to be the first man out. St. John has Mike back off, which he reluctantly does. Once outside, Curtis's men begin firing at Airwolf, and Mike returns fire. Curtis escapes in his car, while his cohort makes off with the money on foot.
Mike pins the men down inside the building while St. John goes after Curtis on a motorbike. Jason has Mike send down a missile to quell the gunfire, and he does so. Jason then chases down the man with the money and apprehends him. The chase winds through the park until St. John and Curtis wind up in a faceoff. They go head-on at each other, then St. John jumps the bike over the car, the shattering windshield getting into Curtis's eyes. Curtis crashes, and is killed by the subsequent explosion as he tries to stumble away from it. St. John, not getting closure in capturing Curtis, is devastated. He stands at Curtis's burning car, tossing his heroin into the fire as the crew looks on.