Middle class Richmond businessman Arthur Groome implicates himself in murder when he flees from the Earls Court rooming house where showgirl Rose Mallory lives, that act of fleeing after he finds her stabbed dead body there in wanting to spare his faithful wife Mary Groome and their two preschool age daughters from the embarrassment of discovering his infidelity. Recanting his initial lies to the police, he feels the need to tell them the truth of what he knows, and thus revealing that he did have a relationship with Rose, when people who knew Rose and of him in her life can place him in her vicinity the evening of the murder. Those people include most specifically Rose's shrewish landlady, Mrs. Rogers, who admits she doesn't much like him. Knowing that he truly does love her no matter what his and Rose's relationship was, Mary stands by Arthur's side through this ordeal, including the high profile trial, a conviction which would mean the death penalty. In the process, a man who has been following the trial approaches Mary wanting to provide her with his support and friendship, she unaware that he is the true murderer, a serial killer who believes he is the arbiter of social morals and thus social justice. Arthur's tribulations are told as a story within a story, that outer story concerning Leslie Scott, a researcher, telling Arthur's tale to his boss, a writer of a book who wants to include a story of an innocent man wrongly convicted.
—Huggo