The Time Engine by Sean McMullen
Wayfarer Inspector Danolarian saw his world's future and did not approve. The inspector knew about time travel because he had once met his future self. What he did not know was that he would be abducted into the future, and wind up on the run with a constable who had shape-shifted into a cat. Danolarian would also find himself marooned in the ancient past, where he would have to recover his time engine from five thousand naked, psychopathic horsemen.A faulty repair plunges him another three million years back in time, to a world of strange, beautiful people living idyllic lives in splendid castles. But things are not always as they seem. After being attacked, he learns from his unlikely rescuer that time travel is not entirely real. A furious Danolarian returns to his own time, planning revenge against the time engine's true builders