In the middle of winter, Alex Martin and Ben Bass, a Guardian newspaper photojournalist specializing in stories in conflict zones and a neurosurgeon respectively, meet by chance when they are both booked on the same Boise to Denver flight, canceled due to weather with no other flights leaving until the next morning. This cancellation causes a problem for both as Alex has to catch a connecting flight to New York City for her wedding the next morning, while Ben has to catch a connecting flight to Baltimore, his home base, for a delicate surgery also the next morning. Overhearing Ben's situation, Alex suggests they charter a plane to Denver, they managing to find a willing pilot in Walter, who believes they can beat the storm. However, in the air, Walter experiences medical distress causing the plane to crash into the snow covered mountains high above the treeline. While Walter dies in the process, Ben, with minor injuries, and Alex, with a serious gash in her leg, survive the crash, along with Walter's golden lab. With nothing functioning on the plane and as no one knows that they were on this flight as Walter didn't file a flight plan, as Alex didn't telephone her fiancé Mark, and as Ben didn't telephone his wife Sarah, they realize their situation is precarious with no one looking for them in this circumstance. While logically minded Ben believes they are better off staying put with the plane, Alex just cannot sit still in her want to try and make their way to civilization. They have to overcome several physical obstacles, but it may be the emotional hurdles that they have to deal with with each other which may be more problematic, especially as deep in their hearts they ultimately do not believe they are going to survive this situation.