I remember seeing a book title that I always intended to pick up but never did. The premise was an individual who was "caught" in a network of portals or passages to other worlds. The catch of the story was that the finding of his way home was a condition for the survival of humanity. This book appeared in hardcover in the early to mid 1980's. The author's name eludes me also. One more bit of information was that the system of portals were called "slideways" I believe. If anyone has any information, I would appreciate it.