The part played by code-cracking in World War II has been revealed in popular film and has also inspired several accounts by code-crackers. Much less well-known is how code-cracking was used in operational situations. In this account the Silent Service speaks through the voice of a young and inexperienced naval officer whose rites of passage to manhood required him to act as a seagoing eavesdropper, a role calling not only for quick intelligence but also for facing up to excitement and danger. Sir Alan Peacock’s story is interlaced with graphic accounts of life on the lower deck, being torpedoed in a Channel action, and how to contribute to intelligence information that was required to foil enemy attacks on Russian convoys whilst facing atrocious weather conditions. The influence this intense experience exerted on Peacock’s subsequent career in economics is also discussed.