Lloyd Christmas, played by Jim Carrey, is a simple-minded limousine driver residing in Providence, Rhode Island. His life takes a turn when he becomes infatuated with his passenger, Mary Swanson, portrayed by Lauren Holly, during her ride to the airport. As fate would have it, Mary leaves behind a briefcase, which Lloyd notices just in time to grab it before a couple of thugs arrive to claim it. However, he misses his chance to catch Mary and is left standing alone on the airport ramp, briefcase in hand, having taken an unfortunate tumble off the jet-way.
Meanwhile, Lloyd's roommate, Harry Dunne, played by Jeff Daniels, is struggling in the pet grooming business, having poured his life savings into converting his van into a sheepdog-themed vehicle. Unfortunately, both men soon find themselves out of work due to a series of mishaps, leading to frustration and despair. The thugs, under the mistaken impression that Lloyd is either a “professional” connected to the Swansons or an FBI agent, decide to take their anger out on the duo. When they show up at their door, armed and aggressive, the two friends barely escape by exiting through the back window, clutching the briefcase.
While in search of new jobs, the thugs target Harry, resulting in the unfortunate demise of his pet parakeet. After their harrowing encounter, Lloyd sets out to buy supplies but ends up getting robbed by “a kind old lady on a motorized cart.” Disheartened by their mundane existence in Providence, Lloyd convinces Harry to accompany him on a trip to Aspen, Colorado, to return the briefcase to Mary. Initially hesitant, Harry is ultimately persuaded by Lloyd's enthusiasm.
The next day, the duo hits the road, oblivious to the thugs following them. Their road trip is filled with comedic mishaps, including a diner altercation with a man named Sea Bass, who retaliates after Harry accidentally throws a saltshaker his way. In a bid for peace, they try to buy drinks for Sea Bass and his friends, but Lloyd's decision to put the tab on Sea Bass's account leads to their hasty escape as they get pulled over briefly by a police officer.
Their journey takes another wild turn when they unwittingly pick up one of the thugs, Joe 'Mental' Mentalino, who tricks them into giving him a ride. Tragically, during a lunch stop, they mistakenly poison him with rat poison, escalating their troubles. As they continue their trek towards Aspen, an inadvertent wrong turn leaves them stranded in Nebraska, prompting Harry to start walking home in frustration. With creativity and determination, Lloyd trades their van for a scooter, reuniting with Harry as they finally make their way to Aspen.
Once there, the friends struggle to locate Mary, spending a chilly night in a park. Unexpectedly, they discover that the briefcase contains a fortune in cash—ransom money intended for Mary's kidnapped husband. Unbeknownst to Lloyd, the duo decides to live lavishly off the money, checking into a luxurious hotel and indulging in extravagant spending, including a flashy Lamborghini and lavish makeovers, sporting outlandish tuxedos along the way. As Lloyd attempts to win Mary's affection—only for her to mistakenly develop a friendship with Harry—the tension between the two friends rises.
In a twist of fate, Lloyd finally decides to approach Mary at her home, inviting her to join him at the hotel to return her briefcase. However, their moment is shattered when Nicholas Andre, a man behind the kidnapping scheme, confronts them at gunpoint. Chaos ensues as Andre discovers the money is gone and bonds Lloyd and Mary to the bed. Just when it seems all hope is lost, Harry bursts in, only to declare he’d rather be shot than let his friend die. A struggle ensues, shots are fired, and in a surprising twist, the FBI intervenes, revealing they had been aware of the kidnapping all along.
In the end, Mary is reunited with her husband, leaving Lloyd heartbroken as he learns she was married all this time. With their dreams dashed and no money left, the duo begins their trek back home, miraculously avoiding another opportunity to be oil boys for bikini models. As they walk off together, they express a renewed sense of hope, with Harry reminding Lloyd, “Someday we’ll get our break too, we’ve just got to keep our eyes open.”
