Having left Susan on Earth in the 22nd century, the Doctor's other companions, Ian Chesterton and Barbara Wright, insist that the Doctor take them back to their own time. Instead the TARDIS lands on Venus three billion years in the past, a time when the planet was not only habitable but inhabited by sentient life forms. As the Venusians attempt to cope with the impending fate of their world, a massive spaceship arrives bearing aliens promising salvation by transporting them to a prehistoric Earth. But is the offer as genuine as it seems, or do these aliens possess a hidden motive that could lead to the Venusians' extinction?
As the third book published in the Virgin Missing Adventures line of Doctor Who novels, Paul Leonard's novel serves as a model for the series in a number of respects. Foremost among them are the Venusians themselves; with their large quadrupedal forms and multiple eye-stalks, there is no need for the reader to pretend that these aliens aren't just actors in elaborate makeup or cheap costumes as was all too often the case on the show back then. Leonard supplements this by portraying their practices and customs as fundamentally different from those of humans, all without sacrificing any sympathy for his characters. Yet in some respects Leonard succeeds a little too well, as when coupled with his writing style it can be difficult at times to understand exactly what is going on in the narrative. While a little more descriptiveness may have slowed the fast pace Leonard establishes in the book, it would have made for a more comprehensible examination of the truly different world he portrays, one that demonstrates the possibilities available when portraying a Doctor Who adventure on the printed page.