Darrow is a Helldiver, one of a thousand men and women who live in the vast caves beneath the surface of Mars, generations of people who spend their lives toiling to mine the precious elements that will allow the planet to be terraformed. Just knowing that, one day, people will be able to walk the surface of the planet is enough to justify their sacrifice. The Earth is dying, and Darrow and his people are the only hope humanity has left - until the day Darrow learns that it is all a lie.