Gordon Williamson, using a carefully selected range of both wartime images and color images of surviving U-boat memorabilia from private collections, describes one hundred iconic elements of the U-boat service and its campaigns. The array of objects includes important individuals and the major U-boat types, through to the uniforms and insignias the men wore. The weapons, equipment and technology used are explored, as are the conditions in which the U-boat crews served, from cooking facilities and general hygiene down to the crude toilet facilities.

Importantly, the enemy that they faced is also covered, examining the ship-borne and airborne anti-submarine weaponry used against the U-boats. The U-boats began the war, though few in number, more than a match for the Allies and created carnage amongst merchant shipping as well as sinking several major warships.