Through GIANTS' STAR, the interactions between humans and "Thuriens" – the distant, Ganymean-descended civilization whose existence was deduced in THE GENTLE GIANTS OF GANYMEDE – took place in virtual space via a supercomputing network operating across star systems. Only at the end did the two races actually meet physically.
By the time ENTOVERSE begins, a regular presence of representatives of both races on each other's worlds has become commonplace. This is where the characters that we have been following through the last three books get to hitch a ride on a returning Thurien starship and experience an alien culture first-hand.
Actually, it isn't entirely alien. As a result of events in the distant past that were uncovered in GIANTS' STAR, an element of the far-off population is of human form and shares human ancestry, along with all its faults and failings. It also shares an all-too-human disposition toward deceit and deception, of which the Thuriens, descended from Ganymeans, have no concept or comprehension. The Terran delegation goes there to help with political problems involving disgruntled minorities and fanatical leaders – familiar enough on Earth, but which the aliens are hopelessly unequipped to deal with.
In the process they discover that the real villains behind all the trouble are not the transplanted humans at all, but a race of beings utterly unlike either Terrans or Ganymeans, who at least share a common origin not only in the Solar System, but of the same reality of space and time. The "Ents" are intelligences that have evolved within the "data space" of the Thurien supercomputer system – along with a world that they perceive as complete with plants and animals, oceans, continents, even a peculiar cosmos.
The "physics" that operates in their world derives from the constraints originally laid down by the system programmers and bear no relation to the laws governing the interactions of objects and forces in the universe that we know. In their realm, magic can indeed happen. On the other hand, the notion of material objects, and space itself, possessing properties that remain the same from place to place and over time is unheard of, and hence, to them, the idea of devices or machines capable of performing repeatably and reliably would appear equally strange. Crossovers from one realm to the other are possible, thanks to the Thuriens' total-sensory VR technology, and the final resolution becomes a tussle between their "magic" and ours.