Roadmarks was published in 1979, but I hadn't previously read it and in fact wasn't even aware of its existence until it was selected as the book of the month by the Classic Science Fiction forum. It is an intriguing read and makes quite a contrast with the more conventional and commercial Amber fantasy series for which Zelazny is now best known.
The early part of the book is confusing. Various apparently unconnected plot threads are set running, characters are introduced without explanation, and it is not at all obvious what is going on. It gradually becomes clear that the threads fall into two basic story lines, both concerned with travellers along the Road. This is no ordinary road, but a road through time; travelling along it moves you forwards or backwards in time, and there are occasional exits to enable the users of the Road to join or leave from particular points in history.
The main story line follows a man called Red, or Reyd, Dorakeen. He is a long-term traveller on the Road, on a permanent search for something even he is uncertain of. The other follows Randy Dorakeen, whose relationship to Red is at first unclear. The story keeps chopping between the two and the true situation gradually emerges, reaching a climax when the threads all come together at the end. I have to say that the instant I finished the book I immediately returned to the start and read the first fifty pages again so I could understand what they had been about!
Generally speaking I dislike books which leave the reader groping for understanding for much of their length, and was initially in some doubt as to whether I would even finish the story. However, Zelazny's writing was good enough to keep me engaged and there was plenty of entertainment en route, with exotic assassins, a planet-destroying robot, intelligent talking books, and even intelligent dragons (again!). Not one of Zelazny's best efforts, but it's interesting for its construction as well as its story, and at fewer than 200 pages is worth the brief reading time.