"The Three Suns of Amara" is a 1962 science-fiction novel by William F Temple, published as one-half of an Ace Double, with the other half being "The Automated Goliath", by the same author. At 80 pages, this is one of the shorter parts of an Ace Double I have read.
The story doesn't make much sense, and this is acknowledged in the opening pages. Amara revolves around three suns, each a different color, and it switches orbits between them in a way that physics can't explain. An earth expedition ship lands there, and a spaceman is sent out to find a lost city. In his search for it, he encounters dangers that defy the laws of physics, or as the cover says:
The tree-trap, the she-trap and the killer id
Because the planet has trees that will...temporally relocate themselves to form a forest, a woman who is a psychic symbiont that changes her appearance depending on who perceives her, and a group of perfectly calm, rational aliens who can manifest people's
id as a killer demon. None of which makes sense. Also, apparently, the earth's government is based on a philosophy where people are appointed
absolute dictators for a month at a time. There was a lot going on here. Also, two dimensional underground aliens? And aliens who laugh maniacally and joke about everything? I didn't know what to make of it all, except that at 80 pages, it was a nice, if uneven fairy-tale.
Strangely enough, the reverse side of the Ace Double, although written by the same author, is widely different in tone and theme.