This is a novel about a submarine, the USS Mako, and the two captains who commanded her on the three patrols covered in the novel. Captain Hinman is assigned to the Mako while she is still being built. He and key members of the crew are able to participate in her construction and have some modifications done to suit their previous experience.

The submarine captains have been claiming that the American torpedoes are faulty and when Hinman discovers the reason, he goes against orders and modifies them. When the modifications make the torpedoes work properly, he tells other submarine captains and as a result is removed from command and misses being court marshaled by a hair.

When a noted disciplinarian ai appointed as his replacement, the crew expects the worse. That worst turns out to be a patrol where the Mako meets the top Japanese anti-sub technician in a battle of survival.

The novel is packed with action, naval political intrigue with positive views of FDR and not so much of General MacArthur. It does include an interesting description of the reception the US sailors received from the Australian population when there on shore leave. ( )