Planet of the Gods - Robert Moore WILLIAMS

Far, far in the future Earth has achieved real peace and is sending out interstellar expeditions, not to conquer, but to explore. The third such expedition, has made it to the Vega system and discovered to everyone's amazement, not only a solar system but two worlds circling the Vega sun that seem to have atmosphere and water. And apparently intelligent life is there as well because something tries, and almost succeeds, in blasting the expedition ship out of space before it can even get close to either one. Damaged, with 3 dead men aboard, the expedition ship semi-crashes and seeks to hide from this obviously hostile civilization. The three dead members of the crew are buried and four of the local inhabitants pay a friendly call. Then during the second night on this planet, one of the dead bodies knocks on the door and wants to come in. Something very strange is going on here.