In the summer of 1974, Mandy River arrives in London to make a fresh start and begins working as nanny to the children of one Lady Morven. She quickly finds herself in the midst of a bitter custody battle and the house under siege: Lord Morven is having his wife watched. According to Lady Morven, her estranged husband also has a violent streak, yet she doesn't seem the most reliable witness. Should Mandy believe her? As Mandy tries to shield her young charges from harm, her friend Rosemary watches from the wings – an odd girl with her own painful past and a rare gift. This time, though, she misreads the signs.