Margaret Saville's husband has been away on business for weeks and has stopped replying to her letters. Her brother, Robert Walton, has suddenly returned after three years at sea, having barely survived his exploratory voyage to the northern pole. She still grieves the death of her youngest child as she does her best to raise her surviving children, Felix and Agatha. The depth of her brother's trauma becomes clear, so that she must add his health and sanity to her list of cares. A bright spot seems to be a new friendship with a young woman who has just returned to England from the Continent, but Margaret soon discovers that her friend, Mary Shelley, has difficulties of her own, including an eccentric poet husband, Percy, and a book she is struggling to write. Margaret's story unfolds in a series of letters to her absent husband, desperate for him to return or at least to acknowledge her epistles and confirm that he is well. She is lonely, grief-stricken and afraid, yet in these darkest of times a spirit of independence begins to awaken. Mrs Saville begins where the novel Frankenstein ends.