Brad (Vince Vaughn) and Kate (Reese Witherspoon) are an upscale San Francisco couple. Having both come from dysfunctional families, with divorced parents and obnoxious siblings with out-of-control kids, the two disdain the idea of getting married or having kids. In an effort to avoid their families at Christmas, the two go on vacation abroad while pretending to be doing charity work there. The third Christmas of their relationship, Brad and Kate plan to go to Fiji, but are trapped at San Francisco International Airport by a fog bank that cancels every outbound flight, and interviewed by a news crew, alerting their families to the fact they're stuck at home for the holidays.