Millie Olson would rather imagine life in the 19th century than face her 21st century life. At sixteen, she's already graduated high school and is expected to attend a top college. All she wants to do is stay home in Indianapolis, take online courses and volunteer at the history museum. She's always been more academic than social and finding a diary written in 1865 by a young girl her age sets her history-loving heart on fire. But her grandmother's insistence that she socialize reconnects her with high school quarterback Zach MacMillan. The last thing Millie expects is a friendship with Zach much less anything more, but as the sparks fly, she's forced to confront her fears with a little help from 1865.