In the U.S. Virgin Islands, casino owner Jack Catlin welcomes Daniel Sims, a nervous man who has arrived by plane with $60 million in stolen diamonds. Sims is concerned the police are following him but Catlin assures him he has nothing to worry about. Catlin checks the diamonds and then shoots Sims dead.
In Washington D.C., MacGyver meets with Senator Rhodes, who admits that he raised $60 million in diamonds as part of an African famine relief fund and thousands of starving people are at risk. His daughter Chris has flown down to the Virgin Islands to try to find a way to get to Catlin but hasn't had any luck. MacGyver agrees to help and flies down to meet with Chris. Chris is less then impressed, figuring a lawyer or FBI agent was coming to help. Chris explains Catlin, a former mercenary, has a personal army working for him and arrived five years ago with enough money to buy a hotel and casino. Catlin is giving a martial arts demonstration by the pool, taking on three men simultaneously. Catlin wins and then meets with his assistant, Tiffany, who confirms their contact in Amsterdam can handle the sale of the diamonds. Catlin tells her he wants everything ready so he can depart in 48 hours.
MacGyver figures there may be a way to steal the diamonds back, but Chris insists it's impossible and illegal. Chris is initially skeptical but decides to plan a break-in. MacGyver insists that he doesn't usually come up with a set-in-stone plan, and notes they're dealing with 200 pounds in diamonds. Chris figures it's hidden in one of two high-security vaults Catlin had built, in his casino and his private suite. First, MacGyver plans to get a look inside the casino vault by going in as a high roller. Chris warns that the casino is rigged but MacGyver plans to get an invitation to store his money in the vault by winning big by cheating.
MacGyver puts on a tuxedo and goes in to the casino, while Chris goes in separately. When a woman gets a drink spilled on her, MacGyver takes advantage of the distraction to hook the woman's dress zipper. When she walks off, the dress comes off and MacGyver steals a pair of casino dice. He then goes to the restroom and uses a shoe polishing wheel and powdered soap to shave the dice to come up seven every time. MacGyver goes on to win big at the craps table, catching Catlin's attraction. He has Tiffany check on MacGyver and she approaches him at the table. When MacGyver bets over the house limit, Catlin agrees to the bet and MacGyver wins again, then switches out the dice, switching out the shaved dice into his drink glass. MacGyver then drops out and Catlin collects the (unrigged) dice. MacGyver asks to see the vault where his money is stored and Catlin obliges. However, as they leave, Catlin takes him to the table and produces the shaved dice from the drink glass. He has his men take MacGyver to his office but Chris trips into them and MacGyver makes a run for it. Catlin and his men chase him down the stairs and MacGyver uses a vacuum cleaner electrical cord to tie a set of doors to make his escape. He then knocks off the valves on two compressed air cylinders to send a bar cart flying into the rest of his pursuers. Outside, MacGyver meets with Chris and they escape on her motor scooter as he informs her the diamonds aren't in the casino vault and must be in Catlin's private vault.
The next morning, Chris is eager to keep on and momentarily holds MacGyver's hand, then draws back. They then go over a photo of the suite and Chris notes that there is a spy camera in the suite. MacGyver figures he has a way to get out the 200 pounds in diamonds but he'll need a riot in the casino. He wants Chris to provide the distraction. He takes out the magnet from the phone and puts it in Chris' shoe with instructions to get it close to the roulette wheel. MacGyver also rigs her ring to mark cards, and tells her to set off the distraction at 2:10 a.m.
MacGyver and Chris go back to the casino and Chris goes inside while MacGyver breaks off the downspout from a drainpipe and goes inside, dressed as a technician. He breaks into the electrical room and uses an alarm clock to rig the wiring to go crazy at 2:10 a.m. He then uses duct tape, a coat hanger, and a mirror to rig the mirror to hang from the spy camera. He then goes to the hallway outside Catlin's suite and slips the mirror over the camera lens, attaching a string. MacGyver picks the lock on Catlin's door while the security guards notice the interference.
On the casino floor, Catlin notices Chris and approaches her, offering some help at the table. Meanwhile, MacGyver gets inside and pulls the mirror rig free, leaving nothing for the security guards to find. There's a suspicious-looking archway and he uses cigar ashes to highlight the laser beams. MacGyver then uses two tubes from a fiber-optic sculpture to bend the beams and crawl through the resulting gap. Ignoring Catlin's Mynah bird, MacGyver finds Catlin's private vault only to discover there's no lock or combination. However, he then comes up with a plan involving the bird.
Catlin is still helping Chris when the security alarm goes off in his penthouse apartment. The guards notify him and he goes upstairs to find nothing amiss. Then he notices the bird has gotten out of its cage and figures it set off the alarm. Catlin checks out the vault, using a handheld sonic device to set off a four-note tone. He goes inside and makes sure the diamonds are secure and then goes back to the casino. MacGyver emerges from hiding and fills four wineglasses with wine, then strokes the rims to produce the proper tones.
On the casino floor, Chris puts the plan into motion. She raises her shoe (with the magnet) up underneath the roulette table, causing the ball to bounce. As the customers start to complain, she goes to the blackjack table and marks one of the cards with her ring. In the penthouse MacGyver gets the vault open. He takes the diamonds to the window with a drainpipe outside, then uses a flower sculpture's oversized petal to prepare to pour the diamonds down the drainpipe. As fights break out throughout the casino, Chris prepares to leave and Catlin arrives to suggest they have a private drink. However, he goes to deal with the riots and Chris slips another magnet inside her compact and onto a million-dollar jackpot machine. The lights short circuit on schedule and the power fluctuates as the jackpot machine goes off and dumps its money.
Once everyone starts making noise, MacGyver pours the diamonds down the drainpipe and Chris runs for the car and opens the trunk. The diamonds go into the trunk and Chris prepares to drive off. However, Catlin realizes she's responsible and goes outside with his men. Chris drives away in her car, going past Catlin's men only to be cut off by another car. MacGyver gets to the car with the diamonds and drives off in the other direction.
Catlin forces Chris to call MacGyver and offers her in return for the diamonds. MacGyver is given instructions to go to a park where Tiffany gets in and holds him at gunpoint, then directs him to an airfield. They drive the car into a cargo plane where Catlin is waiting with Chris. Catlin orders everyone up front but MacGyver reminds Chris about the ring. She scratches Catlin with it and MacGyver shoves him into the cockpit then bars the door. Catlin orders the pilot to take off and go up to 30,000 feet where the lack of air will kill them. Meanwhile, MacGyver straps parachutes to the car and they both fasten themselves in. MacGyver drives off the ramp and the parachutes open, dropping them gently below. Chris kisses MacGyver in triumph as they head for the ground below.