The Floor of the World (Paperback or Softback)

Brian Covington and Pete Wiegand are from Earth. They've been transported in some mysterious way to the planet Brythe They find out that Brythe is going to explode. Who can they trust for help?

They're scientists but can't trust science: nothing seems to be normal on Brythe. There are lights in the sky but no sun and no stars, the length of every day is different and unpredictable, physics is normal sometimes and sometimes weird (how is that even possible, anywhere in the universe?), and the humans on Brythe are not exactly homo sapiens -- but how can they be so similar?

There's no use asking the humans for help. They're swarming in panicky mobs, expecting the end of their world.

There's an alien race called Cortays on Brythe and they want to help. They're building a big machine which is supposed to stop the explosion, but they don't understand how it will work. They're just following instructions.

And the other race of aliens, who call themselves "The Hands of God", designed the machine and are willing to help. But no one has ever seen them, no one knows if they're smart enough to stop the explosion or not, and nobody is certain they even want the machine to work.

The clock is ticking.