Three friends. A reckless pact. A bond shattered by passion, betrayal, and war. From moonlit Cambridge rooftops to suffragette battles in the streets of London and the bloody trenches of France, New York Times bestselling author Kate Quinn weaves an epic tale of forbidden love, buried secrets, and loyalties tested beyond endurance.

1912. Breezy, whip-smart Jass Lennox may be the daughter of a Scottish viscount, but in prewar Britain even a noblewoman has no right to vote, earn a degree, or rule her own life. Between keeping order in her riotous family and slipping away to secret suffragette meetings, Jass encounters two irresistible new friends: Gerren, a Cornish medical student with a healer’s hands; and Ben, a charming scholar consumed by the lure of the world’s highest mountains. Together they introduce Jass to the illicit thrill of scrambling across Cambridge rooftops by moonlight, and atop King’s College Chapel the three swear a champagne-fueled pact of friendship.

It will not survive unchanged.

As Jass joins the jujitsu-trained women defending suffragettes from police attacks and Gerren patches her up when protests turn violent, Ben dreams of a prize no climber has ever claimed: Mount Everest. Thwarted love and dangerous obsession drive wedges within the once inseparable trio and by the summer of 1914, tragedy has torn the three apart…only for war to finish the job.

1918. Haunted by his years as a combat surgeon, Gerren wants nothing more than the peace of his country practice. Instead, a letter from a mysterious blackmailer summons him north to Castle Kinross, a crumbling Scottish fortress transformed into a refuge for wounded soldiers—and the ancestral home of Jasperine, Lady Kinross.

The war is over, but the past the three share is not finished with them. Someone bent on revenge is determined to drag their secrets into the light. To discover who is hunting them, the former friends turned enemies must confront the loyalties, betrayals, and buried truths that once bound all three together—and decide whether the greatest danger at Castle Kinross comes from their mysterious enemy, or from what remains between them.