Andre Norton weaves another spellbinding science fiction tale that takes place in multiple layers of time and during different periods of history. If it is possible to conquer space, then perhaps one can also conquer time. To test this theory Ross Murdock finds himself transplanted to the North Pole to participate in a top secret project. It is suspected that Russian scientists have discovered how to transport themselves back to prehistoric times in order to learn long forgotten secrets. A convicted criminal in his own time period, Ross becomes a volunteer in the government program that hopes to beat the Russians to the discovery of these scientific secrets. Can time travel be artificially created? Can people from different time periods be brought forward from the past through the use of technology? Perhaps the real question is, can they return!