Lucan has been orphaned, Zosine has been deserted, and London in the 1840s is a hostile place for two young girls without a home. Bound together by poverty, isolation and a shared childhood, they set out to make a future for themselves in new surroundings. The austere, puritanical Reverend Pennhallow and his wife adopt them, inviting them to live on their French estate. There, in the large, gloomy house, the two innocents become immersed in a studious, ascetic life and are taught history, literature and the classics. But their suspicions are aroused by a chain of disturbing events, and before long they realize that the cleric and his wife are not all that they seem to be.