Ageless astronaut Sam Austin and the settlers of the planet Citadel have a problem. Former US President Courtney Harrington might be disgraced and convicted of war crimes, but she remains a threat to the newly independent settlers.

Harrington's looking for the means to gain amnesty for the crimes she committed in Target Citadel, and she thinks the very aliens that almost wiped out Citadel offer the chance she needs. If she can secure advanced alien tech for human use, she's confident she'll walk free. Of course, nothing comes without a price-and the aliens want something in return.

Harrington's horrific deal offers up human beings as sacrificial lab rats. Caught up in the deposed president's plot is Sara Albretti, former transport captain and Citadel settler.

In the skies beyond Citadel's star system, the long conflict between Harrington and Austin comes to a deadly conclusion. At stake is the future of Citadel-and possibly all of humanity.

The next chapter in Robert Adrian's Citadel series, Checkmate Citadel continues Sam Austin's remarkable journey from astronaut to founding father of humanity's newest home-a home under threat from alien and human alike.