The well-to-do Lord Montague is assaulted on a fog enshrouded London street on his way to his club, but manages to escape death. He later learns that some unknown assailant is killing off the members of his old army regiment from the Indian War. A Scotland Yard inspector investigating the homicides asks Montague to have the nine remaining members of his regiment assemble at his estate, so as to protect them from being murdered one by one, and so that he can hopefully learn the identity of the assassin, assuming the killer may be one of them.
