It's the height of the Gilded Age, but Elena Bissette's family has lost most of its fortune. The Bissettes still own a home on fashionable Mackinac Island, and they spend summers there in hopes of introducing Elena to a wealthy suitor. Quickly tiring of the extravagant balls at the Grand Hotel, she spends her days walking along the island's rugged coastline. There she meets Chase, a handsome laborer who shares her love for the night sky. The two begin to meet in secret at an abandoned lighthouse, where they work together to solve a mystery buried in the pages of a tattered diary. As Elena falls in love with Chase, her mother contrives to introduce her to Chester Darrington, the island's most eligible bachelor. Marriage to the elusive millionaire would solve the Bissettes' financial woes, and Elena is torn between duty and love.