Inside UFO 54-40 is a Choose Your Own Adventure book of the original series. It's notable for having an ending which can't be reached by making any choices or following any instructions.
Plot Summary
Abducted from your seat in an airplane, you find yourself aboard an alien starship, dubbed UFO 54-40 for its longitude and latitude at the time of your abduction. The ship belongs to a race called the U-TY, who have created a zoo of different alien creatures in hopes of finding the planet Ultima.
Ultima
It's hinted throughout the book that Ultima "can't be found by making any choice", or even by following any instructions. And indeed, the only way to get there is by flipping to page 101.
