During World War II, a seasoned naval officer, Ericson, is given command of the HMS Compass Rose, a new corvette designed for escorting convoys across the treacherous waters of the North Atlantic. The mission is perilous, as German U-boats lurk beneath the frigid waves, presenting a constant deadly threat. Ericson, together with his inexperienced but determined crew, must grapple with the harsh realities of naval warfare, including intense storms, relentless enemy attacks, and personal struggles. The crew forms a tight bond, facing their fears and forging a collective resilience in the face of incessant peril.

As the war progresses, the stakes grow higher, pushing the crew to their limits. With each convoy, the dangers intensify, and the crew's endurance and resolve are continually tested. The relentless sea and the ever-present U-boats create a backdrop of tension and uncertainty. Through a series of harrowing events and difficult decisions, the men aboard the Compass Rose confront the brutal aspects of their mission, realizing the true cost of war. The journey illustrates the courage and sacrifice required of those who traverse the cruel seas, highlighting their fight for survival and the effort to safeguard the essential convoys in a world gripped by conflict.