Famed American playwright Phillip Hannon is in London making revisions to his play currently running in the West End. He is doing this mundane work rather than write a new play since he has retreated from life following the recent and permanent loss of his sight. That retreat from life includes breaking off his engagement to his former secretary, Jean Lennox, who still loves him. One evening at his local pub, he overhears a conversation between a man and a woman that he knows involves criminal activity, what he surmises to be the kidnapping plot of a child in exactly one week's time. The local police patronizingly dismiss his report as the overactive imagination of a blind writer. With Jean and his faithful manservant Bob Matthews by his side - the former with some reluctance on Phil's part - Phil goes on a search to uncover the plot using what little pieces of information he has at hand, which includes the man's name being Evans, the woman, who is involved under duress, working as a nanny for a family whose head is formally a lady, that lady having attended a concert that evening, the family living along a certain bus route, and the nanny herself wearing an expensive perfume well beyond her means. His physical disability is an obvious disadvantage. But what may be working to Phil's advantage is his keen sense of dialogue and its subtext in deciphering the conversation, using his other senses which people with sight take for granted, and people, including the criminals, underestimating him because he's blind.