Haven of Darkness (Dumarest of Terra #16)

Haven of Darkness (Dumarest of Terra #16) by Tubb, E. C.. mass_market edition. ISBN: 9780879972998.

Dumarest had been to many worlds in his long quest for Earth, but none were to entrap him as dangerously as Zakym. A mere stop on his route, Dumarest had thought, but he had not known then of the things that made Zakym of the double-sun unique. One was the daily recurrence of the dead—the time of delusia when spectres walked and criticized the works of the living. The other was the Pact—the unwritten treaty with an unseen species that divided the world forever. In daytime it belonged to humanity; after dark it became a hostile and alien planet. Dumarest thought Zakym would be a mere stopover on his quest, but the living, the dead, and the invisible decided otherwise.