MacGyver is on a Department of Interior-sponsored "Save the Wilderness" expedition to plant five stationary markers as part of an effort to map out a national preserve. Pete and DoI representative Joanna drop him off at a weather station and he assures them he'll be done in a couple of days. Joanna and Pete land at the Phoenix Foundation lake station and Pete reassures her that MacGyver is the man for the job. They check the markers placed by the other men and Pete assures Joanna that they'll soon be trailing MacGyver.
MacGyver finds a Native American totem pole and concludes that it's a warning of some sort. He hears a strange animal roar in the distance and then finds a human skeleton suspended above the totem pole as a guardian. MacGyver plants the first radio marker and hears the same animal roar again. Joanna and Pete detect the signal at the lake station. MacGyver continues on and spots a freighter on a nearby lake. He goes to investigate and hails the crew, but gets no response. He finds a wooden rowboat nearby with scratch marks on it. The back third of the boat is missing and MacGyver improvises using a sleeping tarp to cover the missing section. He rows out to the ship, unaware that someone or something is watching him.
Once aboard the freighter, MacGyver enters a hatch and the door seemingly slams closed on its all. He quickly exits but finds no one. Going back inside, he descends into the bowels of the ship and finds the crew quarters. Food and drink are out on the table and there's a can of red paint smashed on a chair. Beneath a newspaper MacGyver finds a large handprint, nearly twice the size of a human hand. Going back up, he finds a hank of animal hair caught on the metal. On the bridge, MacGyver spots a cup of coffee. As he reaches for it, a huge hair-covered arm smashes through the window. MacGyver ducks out of sight and beneath a table as a huge humanoid beast smashes through the bridge. He slips downstairs and jams the door behind him, then grabs a tool as a club.
As he moves through the ship, he spots a shadow of someone running past him. He closes in and discovers it's a woman. She tries to escape and he tries to explain he doesn't want to harm her. The creature breaks through the bridge door and MacGyver closes the bulkhead door separating them. MacGyver grabs the girl and gets to the bridge, but the creature smashes out ahead of them. MacGyver grabs the girl and jumps over the side with her. The creature throws oil drums at them as they swim to shore. Once there, the girl tries to run away. MacGyver tries to get through to her but she doesn't seem to speak English. He tries to explain the ship's the only sign of civilization for a hundred miles, then starts hiking away and the girl follows.
Pete starts to worry when MacGyver falls behind schedule.
As MacGyver tries to find a language the girl understands, he spots some water and offers her to it. The girl drinks it but refuses to talk.
Behind them, the creature comes ashore and follows them through the woods.
MacGyver makes camp for the night and finally realizes she speaks Russian. However, she admits she speaks English and introduces herself as Karin Graff. Her father works in Alaska and her cousin Alexander helped her to stow away on a ship going to Alaska so she could be with her father. However, the ship stopped and the creature came aboard. Karin thinks it killed Alexander. MacGyver wants to get a better look at it but promises to make sure she's safe first. When they hear a noise in the woods, Karin screams and MacGyver grabs a stick. Three men emerge from the woods: Joe Whales, his brother Dave, and their uncle Len. They're out checking trap lines and hoped to warm up by the fire. MacGyver wonders why they approached so quietly and Karin realizes they know about the creature. The trappers admit something attacked their traps, but Dave doesn't believe it's a creature. Their uncle Len insists it's Sasquatch, and speaks of how he saw it when he was young. They hear another animal roar and see strange glowing lights in the distance.
The trappers agree to stay the night, but the next morning MacGyver and Karin awake and discover they've left early. Back at the station, there's still no sign of MacGyver's remaining markers and Joanna wonders if MacGyver has dropped the ball. Pete insists MacGyver wouldn't go off task but has no explanation for his lack of progress.
As they move through the woods, MacGyver hears an electrical sparking noise and follows it to an oil pipeline. There's a crew working on it and Karin tells MacGyver that they are the men from the ship. He figures they're tapping into the pipeline and stealing oil and putting it on the freighter. The electric arc welder accounts for the strange lights they saw the previous night. MacGyver has Karin stay put while he gets into position to send a signal for help.
Once he's gone, one of the men find Karin and takes her to the others. MacGyver hears her scream and comes to investigate. She claims that she's alone but they don't believe her. Their leader, Bench, tells his man Tenon to take Karin to the ship so they can eliminate her later. MacGyver gets ahead of Tenon and strings up his fishing line across the path and then assembles the rod and jams it into a tree. When Tenon passes, he hits the line and MacGyver pulls back the rod and snaps it into his face, then knocks him out. Bench's men soon find the unconscious Tenon and go in pursuit. MacGyver doubles back to the pipeline and puts three of the remaining radio markers into the pipe. At the station, Joanna notes the discrepancy and tells Pete, who figures it's a signal and has a helicopter prepared.
As MacGyver heads for high ground so Pete can see them, the creature intercepts them. MacGyver struggles with the creature and manages to get on its back. It throws him off and MacGyver discovers he's holding a mask. The creature is a man wearing a voice alteration device. It charges at MacGyver, who flips him with a branch and knocks him out. Pete arrives by helicopter as Bench finds MacGyver and prepares to shoot. The pilot slams the landing gear into Bench, knocking him down a hill.
Later at the station, Karin is leaving for Alaska to be with her father while MacGyver prepares to finish planting the radio markers. Joanna gives him a new pack of radio markers and MacGyver admits that the guy impersonating Sasquatch had him fooled. They hear an animal roaring noise: Pete is playing a tape that they found on the freighter that the pirates were using. However, they hear a roaring noise off in the distance and have to wonder...