Twice torpedoed during the Battle of the Atlantic, LT. Tony Colombo USNR, a former merchant marine officer, is appointed to command a new Navy ship, PC-450, a 173 foot, steel-hulled and much advanced submarine chaser carrying five officers and sixty-five men. After a period of escorting convoys up and down the Atlantic coast, Tony suddenly finds himself escorting ships loaded with Marine Corps equipment all the way to Wellington, New Zealand and then to Brisbane, Australia.Once arrived, he is instantly ordered to begin escorting small convoys up and down the Australian coast. Some weeks later, Tony and PC-450 engage in battle with a dangerous Japanese midget submarine which is attempting to penetrate Brisbane Harbor.In the summer of 1942, as PC-450 begins to escort numerous convoys from Australia to Noumea in New Caledonia, the United States suddenly invades Guadalcanal with the result that Tony begins guiding convoys north in support of the invasion while fending off the multiple day and night air raids that the Japanese throw down The Slot. Subsequently, following the hard fought victory on Guadalcanal, PC-450 participates in the invasion of the Russell Islands and then, during the grinding fight for New Georgia, PC-450 not only helps to fend off Japanese air attacks on the fleet but twice engages in surface actions when the Japanese attempt to infiltrate troops onto the island. Wounded in a sudden air attack that radar could not detect in advance, Tony and Baldy are returned to Brisbane for convalescence and new assignments.