Some time in the 21st century, Professor John Hardwich was flying on an interplanetary cruise ship with his wife and son. Their journey came to a tragic end when their ship was pulled off course by Jupiter's gravity and crashed. Only the professor's son survived the disaster. A local version of the saber-toothed tiger named Tara picked up the unconscious boy and nursed him back to health and then helped him to learn how to hunt and protected him from predators as he grew older, with Jupiter's greater gravity making him superhumanly strong as he matured.