In the wake of apparent self-destruction of the Forerunner empire, two humans--Chakas & Riser--are like flotsam washed up on very strange shores indeed. Captured by the Master Builder, misplaced during a furious battle in space, they now find themselves on an inverted world where horizons rise into the sky, & where humans of all kinds are trapped in a perilous cycle of horror & neglect. For they have become both research animals & strategic pawns in a cosmic game whose madness knows no end--a game of ancient vengeance between the powers who seeded the galaxy with life, & the Forerunners who expect to inherit their sacred Mantle of duty to all living things. In the company of a young girl & an old man, Chakas begins an epic journey across a lost & damaged Halo in search of a way home, an explanation for the warrior spirits rising up within, & for the Librarians tampering with human destiny. This journey will take them into the Palace of Pain, the domain of a powerful & monstrous intelligence who claims to be the Last Precursor, & who now has control of both this Halo & the fate of Forerunners & Humans alike. Called the Captive by Forerunners, & the Primordial by ancient human warriors, this intelligence has taken charge of, & retasked, the Master Builders cruel researches into the Flood--which it may have itself unleashed on the galaxy more than ten thousand years before.