"The Door into Summer" is Heinlein's best and one of my top favorites. I cannot remember how many times I have reread this book, even if not from page 1 till the end, but definitely chapters of it. Besides an amazing plot, the characters have depth and of course the cat with a mind of his own. Heinlein is definitely a great story teller when he sets his mind to it. Our hero's narration of his misfortunes and ultimate revenge and reward is simply delightful reading, with never a dull moment. There are even some sweet moments which are touching. One cannot help but wish the best for our hero and his cat. And this story remains one of the best about time travelling though "Replay" by Ken Grimwood comes a close second. The Door into Summer is simply timeless and will always remain in the front row of my favorite books.