MacGyver smuggles himself into a Medellin Cartel mountain drug camp to free an American journalist, Alexander Shannon, kidnapped by mercenaries to use as a hostage to trade for another Cartel leader. As the helicopter unwittingly hauling MacGyver arrives, Shannon spots it and pauses working. Estebar, the camp foreman, fires a gun near him and warns that the Americans aren't negotiating for him. As the men haul the crate into a tent, the pilot comments that he brought up hot tubs and Estebar realizes he didn't order hot tubs. MacGyver ducks back in the otherwise empty crate. Estebar and the pilot open it and find... a hot tub. Estebar wonder why anyone would send him a hot tub and the pilot figures his bosses sent it.
Once Estebar leaves, MacGyver emerges from beneath the packing. Disguised as a worker, MacGyver picks up some bamboo poles and gets close to Shannon. He tells him to meet him out of the camp. When MacGyver explains he has climbing equipment to get off the mountain, Shannon warns him that he broke his leg trying to escape earlier. The helicopter leaves and MacGyver comes up with a plan. He hides in the mess test for five hours and has Shannon bring him heavy-duty plastic garbage bags and bamboo scaffolding. Using an exhaust fan attached to a salvaged engine, MacGyver finishes assembling the plane just as Estebar arrives. He and Shannon fly over the edge of the mountain and make their escape.
Later, MacGyver returns back to the houseboat with Pete, who thanks him for his help. MacGyver tells him he's taking a break for the next month or two. As he leaves, Pete warns that the Medellin cartel isn't too happy. He turns off the lights and leaves, unaware that someone is watching from the shadows. Once Pete is gone, the person approaches the houseboat.
The next morning, MacGyver wakes up and realizes something is amiss. He goes out and discovers someone has set his houseboat adrift. A woman in a motorboat pulls up and says she lived next door to MacGyver in Minnesota. He finally recognizes her as Zoe Ryan. MacGyver thinks she's nuts and remembers she was always a pest. He tells her that he's not going to help her and she threatens to leave. He finally gives in and Zoe explains that she's a fully certified professor of archaeology and starts talking about how the funding for her project was cut down. When she starts rambling, MacGyver tells her to just ask. Zoe tells him that she needs him to help find the Holy Grail.
Intrigued, MacGyver goes to Zoe's college with her. Coach Grogan confronts her and demands that she come with him. He takes her to the stadium and shows her that the students are digging up the field. Zoe says that the field was built on an Indian burial ground and she appeals to his academic sense. Grogan isn't impressed and tells her to make sure the field is restored before the Saturday game.
Zoe goes to her office but as they open the door, a man in a suit slugs MacGyver and runs away. The office has been searched and MacGyver and Zoe go in. Zoe explains that Erich Von Leer, an international gem merchant, secretly financed her last expedition. When Zoe learned about it, she refused to let Von Leer finance her next expedition. The college cut her funding entirely as a result. Zoe founds the artifact that she brought back, still hidden away in a souvenir pillow. MacGyver walks out and Zoe goes after him. She admits she doesn't have anyone else and shows him Diana's Mirror, made by Ambrose, as 12th century alchemist. MacGyver finally takes a look at it and becomes intrigued.
Von Leer's man Mammon Ahriman to his boss, parked nearby. He admits that Zoe saw him and says that he believes her story about the Temple of the Holy Rose, and the fact it contains a giant ruby. Shima Luca, Von Leer's other assistant, believes the Temple holds the secret of immortal life. Von Leer has Shima kill Ahriman and then they go to deal with MacGyver and Zoe.
Zoe explains that she found Diana's Mirror in an Ottoman temple and insists that it can be used to prove that mankind live together in peace many centuries ago, and will demonstrate the human race can do it again. The Mirror is the key to finding the Temple of the Holy Rose. Professor Wycliff, her mentor, arrives to explain that it contains the Cauldron of Regeneration, otherwise known as the Holy Grail. He offers to help fill in the blanks and they go to the library. Ambrose's papers are there and explain that he built a secret temple. Ambrose placed the key to finding the temple in three artifacts: Diana's Mirror, the Scepter of the Triple Deity, and the Holy Rose itself. The Mirror points to the Scepter, located at an abbey in England. Zoe says she found a phrase in Ambrose's paper, "And once there, exorcise thee, oh unclean spirit." MacGyver thinks the phrase sounds familiar but can't place it. Zoe says that they have to go to London and admits she wants MacGyver there because Ambrose reminds her of MacGyver and his dedication to knowledge. MacGyver reluctantly agrees to go.
Zoe and MacGyver arrive in London and they stop at the hotel. However, she insists on going immediately to the abbey. As Zoe provides the directions to the cab, Shima hears her as he watches the hotel and calls head to prepare an ambush.
A wax museum/torture chamber has been built inside the abbey. The owner, Eunice, greets them and lets them know that she's closing early to go to her hairdresser. MacGyver bribes her into giving them ten minutes alone. They try to think of what Ambrose might have done and MacGyver remembers the expression about exorcising an unclean spirit. He remembers that a Phoenix Foundation employee had a baby and during the baptism, a priest said the same thing. They look for a baptismal font build into the structure and find a weapon display covering it. Removing the panels, they find the font inside. Markings on it match the ones on Diana's Mirror. They place the Mirror to line up with the markings and turn it. Above, three Scepters extend out of the stonework. Each one is tipped with a gem.
Eunice comes in, armed, and captures them. Von Leer and his men arrive and the magnate informs them that they'll kill MacGyver and take Zoe with them to find the Temple. Zoe responds by placing the Scepters on a rack wheel and threatens to destroy them. When Von Leer realizes Zoe cares about MacGyver, he has his man Mammon place MacGyver on a sarcophagus. Mammon and Shima fasten MacGyver down and then activate a pendulum mechanism. The water flows from a tank, hitting a spoon and causing it to ratchet downward. The blade slowly descends and Von Leer suggests she reconsider. Zoe has no choice but to give in. Shima takes the Scepters and Diana's Mirror and prepares to depart. Von Leer takes Zoe with him and leaves MacGyver to his fate.