Mars in the 23rd century has been terraformed, and is being settled by Earth colonists. The outcast "Ruckers"—-former settlers who have revolted—are opposing this immigration. Marswood is set in a near future where Earth has colonized Mars and the United Nations is serving as the Solar System’s supra-government. Slater is a UN peace forces soldier who gets assigned on a secret mission deep into the Martian wilderness, in a combination manhunt for a dangerous criminal mastermind and investigation into hints that Earthmen may not be alone on Mars.