When Dr. Finn O'Neill returns once again to London, he is famed for his pioneering work with immunization. As a human being, however, he has not improved at all. He sees no reason why he should avoid the Bramwells despite his shameful treatment of Eleanor, and even tries to resume their former relationship, even with his young wife ill in the same room.Robert, who has never liked Dr. O'Neill, suspects that Emmaline O'Neill's mysterious and increasingly serious illness may in fact be the result of some unspeakable experiment being carried out by the ambitious Dr. Finn to further his own career. A clandestine visit to the Irish doctor's laboratory reveals a damaging truth with which Robert could end O'Neill's career.As Alice and Robert's wedding draws near, Kate becomes convinced that her job is not safe, since Alice will be bringing her own domestic staff.