When the spring of 1946 comes, Katherine Callahan decides to leave her loving husband and newborn baby so that she may embark upon an unknowingly tragic journey across the famous American highway from Chicago to her sister's home in Burbank. She never does arrive. Fast forward into the present, Kevin Callahan, Katherine's grandson, along with his best friend Cheryl Bachman, traces his grandmother's steps along the now decommissioned road to uncover the mystery surrounding her disappearance. They are armed with only a handful of postcards from Katherine and a Victorian secret code involving postage stamps surrounding a mysterious man from her past. This, along with Cheryl's detective skills and an unusual, paranormal connection between Kevin and his grandmother transcending time itself, bring them closer to the truth as their lives merge in 1946.