Earlier books in the Ross Murdock series, and occasional references in Key Out of Time, reveal that, during the late twentieth century, both the Soviet Union and the United States develop technology making time travel possible.

The two nations compete with each other to explore past civilizations. Aided by tapes belonging to an ancient stellar empire, scientists on Earth make great strides in the field of space travel.

American Time Agents Ross Murdock and Gordon Ashe belong to the first generation of space-and-time explorers; they are driven by a quest for knowledge and a desire to keep ahead of the Soviets.

As the leaders of a group of Samoan and Hawaiian volunteers, Ross and Gordon plan to settle on Hawaika, an island world mentioned in the ancient alien tapes. At first Hawaika seems "a rose world bathed in soft sunlight, knowing only gentle winds." Although the ancient tapes...