Burrowed

If you had to endure a debilitating condition of body or mind, which would you choose? In this world, everyone suffers.
--- In the far-future aftermath of a genetic plague that separated human society into two different groups - sickly yet super-intelligent Subterraneans and healthy but weak-minded Omniterraneans - a brilliant Subter girl is tasked with fixing the broken genetic code to reunite the two groups in the next generation. But when a newer plague turns fatal for the surface-dwelling Omnits, the only group able to reproduce (giving birth to both Subter and Omnit children), Zuzan must find a cure or humanity won't simply remain divided, it will become extinct.

But there's more conflict at hand than a broken genetic code. The fragile connection between Subters and Omnits has frayed to the point of breaking - to the point of war - and it will take more than genius to repair; it will take heart.