London, 1927. Frederick Rowlands, an injured war veteran, works as a switchboard operator in the City. After being blinded by shrapnel in the First World War, Fred had to adapt and quickly develop his other senses to survive in the bustling city post-war. When Fred comes into contact with elegant socialite, Lady Celia West, she instantly charms him. When he starts listening-in to Celia's private calls to her secret lover, Fred's boss, Gerald Willoughby, he overhears something very sinister ... When a murder victim is discovered, Fred takes it upon himself to risk everything to protect the women he has fallen in love with.