What is the main conflict in The Robots of Dawn by Isaac Asimov?

The Robots of Dawn completes a trilogy of detective novels set a thousand years in the future in which an Earth police detective, Elijah Baley, works with a humaniform robot, R. Daneel Olivaw, to solve bizarre murders. Here they work on the planet Aurora and determine that a second humaniform robot, R. Jander Panell, has been killed to prevent Earth from being frozen out of Galactic colonization.