Darrow is a Helldiver, one of a thousand men and women who live in the vast caves beneath the surface of Mars. Generations of Helldivers have spent 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. Mars is habitable - and indeed has been inhabited for generations by a class of people calling themselves the Golds. The Golds regard Darrow and his fellows as slave labour, to be exploited and worked to death without a second thought.

With the help of a mysterious group of rebels, Darrow disguises himself as a Gold and infiltrates their command school, intent on taking down his oppressors from the inside.

But the command school is a battlefield. And Darrow isn't the only student with an agenda...