USS Teuthis Saturation Dive Team Officer-in-Charge (OIC) Mac McDowell is leading his submarine team on a mission to lay SOSUS arrays under the ice in the Arctic when they clash with a new Alfa-class highly automated Soviet submarine. Overwhelmed by mechanical problems, the Soviet crew abandons their sub near Pt. Barrow, Alaska. The Teuthis skipper launches DSRV-1 Mystic, so Mac and his crew can board the empty sub and gather intelligence. The arrival of an even more advanced Soviet sub leads to breathtaking underwater clashes with the specter of war looming. Will the Soviets sink Mac and his crew to their watery graves, or will Teuthis safely return to Alaska where Mac's new love, Kate, anxiously awaits his return?