MacGyver has been assigned to meet with four Phoenix Foundation employees in high-stress positions on a five-day overland hike to help them relieve stress.
One of the men stops at a rest stop. As he goes inside, one of twelve escapees from the county jail follows him in and kills him. The prisoner then dumps the body in the woods and searches his clothes. He takes the Foundation employee's wallet and gets into his car. As the radio plays about the roadblocks, the prisoner sees the folder concerning the Phoenix retreat and drives away.
MacGyver meets with the three men... and the prisoner. MacGyver calls off their names one at a time and they introduce themselves: Henry Colter, Chuck Laraby, Tony Parisio, and Dr. Fred Beam. None of them have met each other before. MacGyver talks of how they're all suffering from "the invisible killer": work-related stress. They start with a hike to Cascade River. Once they're they'll cross the bridge and make camp for the night. MacGyver is prepared to leave the map behind, but Parisio insists on taking it just in case.
Two kids playing near the rest stop find the corpse.
Dr. Beam has trouble with his pack, and MacGyver adjusts it, noting that it's set for someone smaller. Beam claims that his son wore it last. Laraby is having trouble with his shoes, which don't seem to quite fit. As they continue, Colter notices some berries and picks some to eat.
Pete meets with the local police to meet with Sheriff Maxwell, who is heading the investigation. Maxwell warns that the dead man was a Foundation employee.
Laraby starts to fatigue and MacGyver calls for a break. Colter is admiring the plant life and knows a lot about biology. Parisio tries to tune in a radio and Beam angrily tells him to shut it off. A newscast about the prisoner escape comes on and when Parisio refuses, Beam slaps it out of his hand. Beam apologizes, admitting he has a lot on his mind. As they start up again, Parisio checks the distance with his binoculars and claims he's just looking for bears.
The five men arrive at the suspension bridge. Laraby is nervous and admits that he has acrophobia. They cross over, Laraby next to last and MacGyver behind him. Laraby freezes halfway over and yells at MacGyver to stay away. When MacGyver comes to get him, Laraby knocks him over the side of the bridge and MacGyver hangs on, a hundred feet above the river. Colter comes out to help, edging past Laraby, and pulls MacGyver up. He then punches Laraby, stunning him long enough to get off the bridge. On the other side, Laraby apologizes and MacGyver note that acrophobia wasn't on his application.
Sheriff Hubbard refuses to send men out to check the Foundation base camp, insisting he has more pressing priorities. He asks Pete to have some patience. Pete refuses and insists on going to the base camp. Hubbard sends his underling, Walker, to escort Pete.
As the men make their way through the forest, Parisio calls out and Beam once again snaps at him. They go past a lookout tower and a ranger, Liz, comes out with a gun and demands ID. She explains that prisoners escaped earlier and she's being cautious. Convinced, Liz invites them to the tower for coffee.
Pete and Walker arrive at the base camp and Walker finds a hank of hair. They figure he cut off his hair to disguise his appearance and joined the stress relief program.
MacGyver and Liz go strolling outside the tower and MacGyver wonders if the news broadcast had any specific description. Liz admits that they didn't. Parisio starts taunting Laraby over his acrophobia and then jokingly asks which of them might be a convict. Laraby snaps at him and goes outside. Meanwhile, MacGyver notices Liz carving a birdcaller. She talks about how she took the job to help her get over a divorce. She gives him the birdcaller and tells him to whistle if he wants company and call a bird. As they leave, she tells them about another path through the pass, one that's shorter but tougher.
Walker and Pete come to the bridge and discover that someone dropped the cables on the other side. They go to the lookout tower to radio for help.
In the woods, MacGyver notes that Colter is a skilled biologist. Laraby finally remembers Colter as a man he's been talking with via the fax. Colter recognizes him as well, apparently. That night, they make camp and MacGyver notices that Beam fieldstrips his cigarettes. Beam claims he was in the Marines and wonders if MacGyver thinks one of them is a convict. They start to argue among each other and Parisio jokingly confesses, pointing out that Laraby escaped with him. Laraby takes it seriously but there's nothing they can do. MacGyver offers to take a look at the broken radio, even though one of the batteries is missing. Once the men go to bed, one of them gets out a gun... and another one strangles him.
The next morning, the men discover that Beam is dead in his tent. MacGyver notices some berries lying on the sleeping bag: the same ones that Colter picked earlier. Colter is gone and Parisio figures Colter is the convict. Laraby wonders why he killed Beam and not the others. MacGyver notices that the coffee has more of the holly berries in it, and they're poisonous enough to kill all of them. Parisio wonders why Colter would have killed MacGyver when he's the only one who can get them out, but MacGyver realizes there's someone else who can get them out.
Walker tells Pete that Liz has finally contacted them. Someone took the fuse out of her radio.
Hubbard and Pete contact Liz and start to warn her. Colter comes up behind her as they give her descriptions of the prisoners. As they tell her that one of them is going by the name of Harry Colter, Colter smashes the radio.
MacGyver, Laraby, and Parisio arrive at the tower and discover the broken radio and the missing Liz. MacGyver goes after Colter and Liz and tells the two men to try and fix the radio. Parisio apologizes to Laraby, admitting he thought he was a convict.
MacGyver approaches Colter and Liz and uses the birdcaller to signal her covertly. He then gets ahead of Colter and uses fishing line and branches to rig a small hut and then sets a fire underneath it. When Colter sees the fire and approaches, MacGyver pulls the string, spraying the ashes into Colter's face and distracting him long enough for MacGyver to knock him out.
Hubbard and Pete are called out when a second corpse is found: another Phoenix employee. They realize there are two convicts with MacGyver.
MacGyver and Liz take Colter back to the tower. Laraby tells them that Parisio fixed the radio and then went into the woods. They give Laraby the rifle and tell him to watch Colter. In the tower, Liz and MacGyver discover the radio is working but the microphone is missing. Below, Laraby tells Colter that he killed Parisio and wants to know why Colter tried to kill him with the poison. Laraby finally releases him. MacGyver spots them from above and locks the tower door. He goes to work with the sighting telescope, a bullhorn, and vinegar. Laraby calls on them to come down while MacGyver has Liz smear grease in the telescope. MacGyver covers cotton bedding with vinegar and pepper. When Laraby comes up, MacGyver uses the bullhorn as a pressure device to fire the wadding into Laraby's face. Blinded, he stumbles back, falls, and breaks his leg.
Colter takes the gun and, ignoring Laraby, goes up the tower stairs. MacGyver and Liz open a hatch in the floor, cover it with a rug, rig a rope, and then hide in the rafters. When Colter comes up, MacGyver distracts him and he steps back on to the rug, falling through and ending up dangling from the rope.
Later, Hubbard uses the incident to get additional reinforcement and Pete promises to continue the program and name it in honor of the dead men. Hubbard gets word that his kids have measles and wants to know when the anti-stress program will be starting up again.