The Dosadi Experiment

Beyond the God Wall. Generations of a tormented human-alien people, caged on a toxic planet, conditioned by constant hunger and war — this is the Dosadi Experiment, and it has succeeded too well. For the Dosadi have bred for vengeance as well as cunning, and they have learned how to pass through the shimmering God Wall to exact their dreadful revenge on the universe that created them...

From author Frank Herbert, creator of the Dune series. The Dosadi Experiment.