In 1540, newly married and pregnant Isobel Devlin vanished from a tiny island in Lancashire, never to be seen again.

In 2020, leaving London for the first time since the pandemic began, Nicole Rayburn and Kyle Walsh head to a guesthouse in the Lake District for a much-needed holiday. Across from the historic manor house, on an island in the middle of a lake, are the ruins of Montrose Abbey, the last known abode of Lady Isobel Devlin. Intrigued, Nicole begins to research Lady Isobel's disappearance as the subject for a new book and calls on her history-loving friend Reverend Hargreaves for help.

As Nicole unearths long-forgotten truths about the mysterious Lady Devlin, finding many gaping holes in the story of her disappearance, she must fight for her own happiness against a rival whose claim to Kyle's heart might be stronger than she expected.