After a harrowing war patrol in the Sea of Japan, the US submarines of Wolfpack 351 are low on fuel, torpedoes, and morale. Their only means of escape is a narrow passage teeming with enemy aircraft, mines, and coastal batteries—and guarded by a menacing Japanese fleet led by a legendary admiral hell-bent on stopping them.

Facing the imminent destruction of the entire wolfpack, and with few options remaining, the American admirals in Pearl Harbor turn to an aging submarine, the only boat close enough to help. With time running out, the USS Aeneid—a V-boat from another era—must spring the trapped submarines from their watery prison before they meet their fates under the hull-shattering wrath of the enemy's depth charges.