This is essentially an updated 'swords on Mars' book, in the old tradition of Burroughs, Kline, Moorcock (yes, that Moorcock) and others. Mars has been terraformed and settled by humans, but the terraforming has gone wrong and much of Mars is an alien jungle. Many of the humans have gone 'native' and challenge the authority of the UN troops. A crack team must penetrate deep into the jungle to investigate a mystery that threatens all civilization on Mars! A fun easy read, not nearly as good as his other books (and similar in some ways) but I enjoyed it. ( )