Like all Earthmen, detective Elijah Baley has a terror of open landscape., of the naked sun.

Reacting in fear of the technological superiority of the Outer Worlds, the people of Earth have hidden themselves in vast underground cities, nursing a hatred for Spacers. The fifty Outer Worlds of the Spacers together are home to fewer people than planet Earth. And home to many, many more robots. Earthmen hate Spacer robots, too...

But Baley doesn't. He once had a robot partner, R. Daneel – and when the authorities of the planet Solaria request terrestrial assistance in investigating a murder, Baley is once again teamed with Daneel. He is the first Earthmen in a millennium to travel to the Outer Worlds... and he must endure the glare of a sun far more deadly than Earth's.

(From Goodreads)