 The story is about an Earth astronaut who is attempting to retrieve a space probe that has crashed on a giant Earth-like planet, a planet that is so large that the gravity is 700 times the gravity on Earth. However, the planet is spinning so fast that centrifugal force means that gravity on the equator is only three times that of Earth. So he's able to land and to survive with the help of a special suit, and he discovers local intelligent life whom he gets to know and recruits and they help him retrieve the space probe. Now this, if you've listened to my other reviews, you've heard me use the term hard sci-fi. Well how Clement defines the term hard science fiction. He starts with the science and he sticks to it rigorously and mercilessly. He starts with a premise. He says what if there were a planet so huge that the gravity was 700 times Earth and what if it was spinning so blah blah blah and he sticks to the real physics of what kind of life would there be? How would it survive? How would it affect humans who tried to survive there? What would be the consequences of these conditions? And it's truly fascinating stuff and he tells a good story. If you're a beginner to science fiction though, you should not start with Hal Clement.