The Straits of Hell is a sequel to Valhalla that takes place fifteen years in the future. Several Earth submarines go back to Valhalla and fight along side the Black Glove fleet for the safety and well-being of both Earth and Valhalla. Dr. Kurenof has advanced in technology and becomes a major threat to Earth's future. Some of the main characters in the novel Valhalla return to fight and die for their planet. More of the wonderful and terrible features of the planet Valhalla come to light. The Straits of Hell brings the reader further along in the series and give them a hint of what will happen next.