In 1954, an expedition found what seemed to be a missing link in the evolutionary chain: an ancient, immensely powerful amphibian creature. Scientists tried to tame it, break its will, and even change its very being with surgery and torture, but the beast rebelled, killing nearly all in its way. But was the creature truly a throwback, a freak survivor of some prehistoric era—or was it something more?

Six decades later, one scientist attempts to find out, using a time machine to journey into the past. What he finds not only shatters his vision of what the Creature might be, but could change the history of the human race forever.