Billionaire, software mogul, Adam Pi has everything in life with the exception of positive memories from High School. He begrudging goes to the 20th reunion and has such an amazing time he finds himself wondering “If I knew then what I know now” and offers the entire grad class one year’s salary to come back and do one more month of the 12th grade.

At the height of her career, investigative journalist Hannah Dunbar finds herself wondering what would have been had she stayed with the love of her life, Ben, 10 years before. When Santa Claus hears her “what ifs?” as a Christmas wish, he transports Hannah to a version of her life where she and Ben started a family.

Four couples meet for Sunday brunch only to discover they are stuck in a house together as the world may be about to end.