Editor Caroline Holt is on her way to her late mother's upstate cabin in Hudson to spend the holidays. She was supposed to be in London, having a holiday romance. But this Christmas, she isn't in the mood to get her heart broken again. Caroline loves being an editor, but in the last year burnout has taken over. She has been mourning her mother, and she is looking to get that spark back.

In the cabin, Caroline finds a letter addressed to her mother. It's in a red envelope, and the return address is Santa's Little Red mailbox, in Aspen, Colorado. The letter is from a man declaring his love for her mother. He'll be waiting for her in front of the Little Red Mailbox at three pm on New Year's Eve.

Unable to ignore her curiosity, Caroline takes the next flight to Aspen to meet her mother's mysterious lover, but things start getting complicated when she meets another man in town. The more they run into each other, the more she is drawn to him. And when Caroline finds out the truth about the person her mother had loved, she unravels secrets of her own past.

By the end of Christmas week, Caroline gets a chance to rewrite her own destiny by confronting her fears of loving again and possibly leaving behind what she thought was a perfect life.