From the introduction: Welcome to sunny Marduk… not really. Marduk is a jungle hell world, a distant outpost of the Empire of Man (no, not that one… or the other one. This one is ruled by the MacClintock Dynasty.) where it rains five times a day and practically every living thing is out to kill you. Some of the inanimate stuff too. From killerpillars to vampire moths, from apex predators to stinging insect analogues, from flood, sea-monsters, cannibals, barbarians, and faulty equipment, this is a world that, in the canon, winnowed 200 of the best of the best of the Imperial Marines down to a scarce few. And now you get to join them… from the beginning.