A pair of interwoven stories set in the present and past follows Ellie Haworth, an ambitious journalist who discovers a trove of secret love letters from 1965 and becomes determined to solve the mystery of the forbidden affair at their center. As she uncovers the story behind Jennifer Stirling, the wife of a wealthy industrialist, and Anthony O'Hare, the financial journalist assigned to cover him, Ellie's own love story unfolds with the assistance of an earnest, endearing archivist who helps her track down more letters.

The mundane life of a 39 year old introvert is disrupted when she begins a steamy but contentious affair with a much younger Man.