In Survival Machines, book two of The Origin Trilogy, John and the army of survivors continue the search they started in Darwin's Soldiers. Who brought them to this bizarre world and for what purpose?

Discoveries are made and battle fought as the allied army are drawn into a world populated by alien armies who have survived the same tests as them. Factions fight to get to the core: a prized location which offers them the answers they are all searching for.

But a new threat rises, in the hyper-evolved Tathon, who threaten to tear the new world apart. The very survival of all species is at risk as John desperately tries to get the factions to work as one and defend the core.

Will their adaptations be strong enough against their new foe? And will anyone survive?