Emma Hendricks is a strong, independent journalist known for getting at the truth. She has everything she's ever wanted until her fiancé leaves her alone and devastated a few days before the wedding. She's the "go to" girl for finding answers to unsolved mysteries, but even she can't figure out what happened. Everything she believed in was a lie. Needing to get away, she heads to Beacon Bay--a small coastal town in Maine--for the summer. After finding an antique bottle wedged between two rocks in the ocean, she frees it only to discover there's something inside. Breaking the bottle to retrieve her treasure, she cuts her hand.
Kathleen Connor is the daughter of an artist mother and fisherman father, living in Beacon Bay during the 1940's in a time of war. She should be happy with her lot as a school teacher, but she's always felt she was meant for something more. After pressure from her parents, she finally marries with hope for a brighter future. Her husband runs the local store and has the respect of the community, but soon after their wedding, he begins to abuse her, turning her dreams into a nightmare. She runs away and becomes an outcast in a little cabin on the coast.
Meanwhile, present day emergency room doctor and widower, Logan Mayfield, stitches Emma's hand. She shows him a faded, yellowed map with a coded message written at the bottom and signed, Until Tomorrow, followed by the name Kathleen Connnor. Deciphering coded messages had been a hobby of his in college when he took an art history class and got caught up in hieroglyphs. Emma is the most interesting person he's met in a while, but he can't afford to be interested in anything but raising his son. His wife died six years ago from complications due to childbirth, but no one knows what really happened.
In a place far away and decades ago, Joseph Henry Rutherford III is serving his country the best that he can. He comes from a wealthy family in shipbuilding, living in Beacon Bay as well. They choose the woman he is to marry, and he doesn't protest since he's lonely and sad after all the horrible devastation he's witnessed. Needing to connect with someone, he writes a long, heartfelt letter to her but it's mistakenly sent down the coast to Kathleen's address. She tells him right away, but he doesn't care. The connection they form through letters creates a love they never imagined possible. When he returns from the war, they form a system of coded letters to secretly meet. Those are the letters Emma and Logan decipher to uncover what really happened and set the record straight. When Emma's past catches up with her, will she fight for what she really wants? Will Logan learn to forgive himself and take a chance on something real? Or will history repeat itself?