Not a sequel, but a retelling. Unhappy with his original novelisation of the movie, Asimov decided to take the idea back to the drawing board and write his version of the story. While book doesn't have Raquel Welch, nor Innerspace's Meg Ryan, it does have a whole new cast. Not quite the pace or excitement of the film, the suspicion is that Asimov was too keen to prove that he could write the story without the perceived issues with the first one...