Twenty years after their impulsive marriage, Maggie and Bill Barrett are happily settled into the quiet comfort of their dream home with their three beautiful children. Then, the day after Christmas 2004, their world is shattered apart.

Natalie and Tom have been best friends forever. But Tom wants more, and he’s going to prove to Natalie that they were meant to be together. He makes a wildly romantic proposition: spend 26 weekends together, indulging in a different activity from A-to-Z. In six months, he argues, they will be desperately in love. The cautious Natalie—still heartbroken over her ex-boyfriend Simon—isn’t so sure.