Robert Heinlein once wrote a book called The Number of the Beast, a fun frolic about a scientist who invents a time/space device and his family. However, unbeknownst to most of his fans, Heinlein also wrote a parallel novel called The Pursuit of the Pankera: A Parallel Novel About Parallel Universes.
The two novels begin the same way, however, once the family starts traveling between universes, the stories diverge. Number of the Beast has the Carters and the Burroughs meeting members of an English penal colony on Mars and ending up with Lazarus Long on Tertius. Pursuit of the Pankera has them on Barsoom and working with the Gray Lensmen.
I’m not sure which book I like best. I’m still only partway through Pursuit of the Pankera, but they’re trying to exterminate the alien “Black Hats” which have infested several parallel Earths, while in Number of the Beast they were trying simply to expose them and find out where they came from.
If you like Heinlein, this “lost” book is an interesting parallel to Number of the Beast. Load it onto your kindle and get started!
