DuringshoppingforChristmas,FrankandMollyrunintoeachother.Thisfleetingshortmomentwillstarttochangetheirlives,whentheyrecognizeeachothermonthslaterinthetrainhomeandhaveagoodtimetogether.AlthoughbotharemarriedandFrankhastwolittlekids,theymeetmoreandmoreoften,theirfriendshipbecomingthemostpreciousthingintheirlives.