The Rival Submarines

1919. The Great War has ended, but beneath the waters off Portsmouth, a different kind of battle rages. A foreign submarine has been threading through British defenses, leaving cryptic warnings attached to the anchors of the King's battleships. The Admiralty is baffled. The fleet is on edge. And the only man who can solve the mystery is Sub-Lieutenant Arnold Hythe, whose curiosity may be both his greatest asset and his deadliest flaw. What begins as a routine investigation becomes a descent into deeper waters than Hythe ever imagined. The submarine's enigmatic commander, Captain Restronguet, operates by his own mysterious code, part visionary, part saboteur, entirely unpredictable. As Hythe races to expose the threat before the fleet's practice maneuvers begin, he must navigate not just the depths of the ocean but the treacherous currents of military politics and personal ambition. The water is cold. The secrets are dark. And the truth may be more dangerous than the enemy. This is a lost gem of early submarine fiction, where the thrill of technological warfare meets the elegance of a good puzzle. For readers who crave maritime adventure with genuine mystery at its heart.