|Ace paperback, fourth printing, 1978. Cover by Dean Ellis.|
"Blake Walker has never really known who he is, or where his strange flashes of intuition come from. But when they help him to foil a murder, he finds himself drafted in a frantic chase for a criminal genius - a chase that will lead him through almost infinite levels of alternate realities.
The stakes are high. For if he succeeds, he saves Earth from the ultimate desecration. If he fails, Earth is lost...and he is lost to earth forever, stranded at THE CROSSROADS OF TIME."