The story spans two generations of the Armadale families and the complex plot combines several of Collins's favourite themes, including the supernatural, identity, murder and detection. The novel has a convoluted plot about two distant cousins both named Allan Armadale. The father of one had murdered the father of the other (the two fathers are also named Allan Armadale). The story starts with a deathbed confession by the murderer in the form of a letter to be given to his baby son when he grows up. Many years are skipped over. The son, mistreated at home, runs away from his mother and stepfather, and takes up a wandering life under the assumed name of Ozias Midwinter.