The Door into summer

Dan Davis, an electronics engineer, had finally made the invention of a lifetime: a household robot that could do almost anything. Wild success was within reach--and Dan's life was ruined. In a plot to steal his business, his greedy partner and greedier fiancee tricked him into taking the "long sleep"--suspended animation for thirty years. But when he awoke in the far different world of AD 2000, he made an amazing discovery. And suddenly Dan had the means to travel back in time--and get his revenge. Once again, grand master Robert Heinlein's genius shines through, illustrating why his books have sold millions of copies and won countless awards.