When Lt. Sam Chance, a newsman in civilian life, takes over the submarine chaser Seven in 1943, he does so with practically no more useable experience than his green, fumbling, sea-sick crew. But the intrepid Seven makes out. In a series of exciting, sharply etched adventures, it undergoes hardships typifying all the little World War II ships of its class. It fights U-boats off Central America, Japs in the Pacific, unsympathetic flag officers aboard command ships. In a dramatic, movie climax it is boarded by Japanese, saved, and then blows up an enemy sub. Characterizations and routine Navy sexual campaigns help out, but it is the action which makes this novel a little more than routine stuff.