As Queen Victoria's reign reaches its end, Grace Farringdon dreams of polar explorations and of escape from her stifling home with her protective parents and eccentric, agoraphobic sister.

But when Grace secretly applies to Candlin, a women's college filled with intelligent, like-minded women, she finally feels her ambitions beginning to be take shape. There she forms an Antarctic Exploration Society with the gregarious suffragette Locke, the reserved and studious Hooper and the strange, enigmatic Parr, and before long the group are defying their times and their families by climbing the peaks of Snowdonia and planning an ambitious trip to the perilous Alps.

Fifteen years later, trapped in her Dulwich home, Grace is haunted by the terrible events that took place out on the mountains. She is the society's only survivor and for years people have demanded the truth of what happened, the group's horrible legacy a millstone around her neck. Now, as the eve of the Second World War approaches, Grace is finally ready to remember and to confess . . .