Without giving the story away, Red Mars begins with a team of people from Earth traveling to Mars to establish a permanent colony. The book focuses on the travel to Mars and the setting up of the base. It discusses the construction of the base and exploration of Mars. What makes it very interesting is the back and forth between the characters. The author does a wonder job bringing forth the conflicts that arise when people are in small, closed environments for a long period of time. The book also focuses on the differences in opinion on how to terraform Mars.
On top of all of this the book goes into great detail how personal relationships, both platonic and romantic, affect the working relationship of the whole colony community.
I'll sum this book up in two words: Absolutely Fantastic!!!