170 years from now, aliens decimate Earth. A relative handful of humans survive, hidden in deep subterranean enclaves that offer some protection from surface radiation. Although the main attack is now seven years in the past, one alien ship remains in orbit, and the conquerors are not content merely to let humanity lick its wounds.

Humanity is greatly diminished, but a few tens of thousands survive, sheltering in huge compounds deep beneath the ground, prepared many years ago against the possibility of nuclear attack by some rogue country.

Five heroic individuals in Compound A-3 take it upon themselves to find a way to save humanity, for in a matter of a few more years, attrition due to radiation will finish the job that the aliens began with their initial attack.

Sethra, a computer programmer and electronics expert, joins forces with Byron, a roboticist with a talent for acquisition and reallocation of others' belongings, as well as with the compound's chief medical doctor, Eddie, and two brave women, one of which is more than she seems.

How do you defeat aliens while hiding in your last refuge hundreds of meters beneath the irradiated crust of the Earth, especially when the aliens are far more sophisticated? --William Bryan Miller