One Sunday in February, an unnamed woman is accompanying her sick partner Stem on a motorcycle ride towards Greyback, a mountain in southern California. On the following Monday, they plan on getting a divorce on account of Stem's health, though the woman had resisted this as much as she could. On their way to San Bernardino, near where the mountain is, Stem steers around some traffic, taking winding back roads. They lose track of time and where they are, arriving sooner than they realized. They stop at a gas station, where the woman goes inside while Stem examines the motorcycle, making sure it is in working condition. The woman buys some food, warm beer, and ointment for Stem. Back outside, they ask the attendant about the trail on the mountain, and he tells them that they'll never make it up there this time of year on a motorcycle because it's too cold and steep. The couple ignores him and continues on their journey. The ride is rough and tiring, and they need to stop to take breaks to eat and make sure the bike isn't overheating. The woman does her best to hold out longer than Stem. As they getting higher and higher into the mountains, they came up to a single-lane control road that was currently closed in their direction to let cars come from the opposite direction. Stem goes around the barrier and drives up the road. They nearly run into several vehicles, but they are able to maneuver around them without falling off the steep road. They come to a lake and then find the trail going up Greyback, which is covered in clouds. As they travel up the steep mountain, they come across places where landslides have blocked the trail, forcing them to dismount and walk around the rocks. They came to a small ravine where they couldn't easily cross the bike over, but Stem did not want to turn back. The woman climbed over first, and then he started the bike and ran alongside it and scaled the gap. After this, the motorcycle died, so they had to push it up by hand. They get drunk on the beer from the gas station, and it starts to thunder around them, and it gets dark. Worn out, bruised, and bloody, they continue up the trail as lightning begins to crack around them. When the motorcycle hits a rock, the woman is knocked to the ground. Stem forced the bike over the rock, but he pops the tire in the process. A flash of lightning illuminates the trail. The woman, who's still on the ground, sees Stem a quarter of a mile ahead of her. He tries to refuel the motorcycle, but he spills the gas and it catches fire, burning him alive. The bike then explodes. Knowing she is doomed as well, the woman struggles to crawl further up the trail, hoping that her body will be found higher than Stem's.