They are the Jerrollites, an alien race with a long history of ruthless conquest. They target a planet, brutally overwhelm its inhabitants, and pillage its resources before moving onto their next target.

This time, they’re targeting Earth.

Former military intelligence officer Mark Hunter is pulled back into service for one more mission: determine when and how the Jerrollites will attack. Hunter’s quite capable of completing his dangerous assignment, but his superiors sent him too late.

With Earth’s defenses reduced to a single starship, Hunter and the crew of the Hercules devise a desperate plan to save what’s left of their planet. An untested weapon lies hidden behind the Pentagon’s walls-a weapon capable of destroying the Jerrollite home world with a single shot.

To succeed, the Hercules must return to Earth, retrieve the weapon from the occupied world, and fight through Jerrollite forces to their home planet. It’s a last-ditch effort to save what’s left of humanity. Or at least exact some measure of vengeance for the loss of Earth.

A tale of resolve and revenge against overwhelming odds, Gravity’s Hammer explores what might happen should humanity ever find itself outgunned and outmanned.