After the fall of the Galactic Empire, lawlessness has spread throughout the galaxy. A lone gunfighter makes his way through the outer reaches, earning his keep as a bounty hunter.

Hundreds of years from now, the last surviving humans discover the means of sending consciousness back through time, directly into people in the 21st century. These "travelers" assume the lives of seemingly random people, while secretly working as teams to perform missions in order to save humanity from a terrible future.

Many years ago, the last remnants of humanity were forced to retreat behind the towering walls of a fortified city to escape the massive, man-eating Titans that roamed the land outside their fortress. Only the heroic members of the Scouting Legion dared to stray beyond the safety of the walls – but even those brave warriors seldom returned alive. Those within the city clung to the illusion of a peaceful existence until the day that dream was shattered, and their slim chance at survival was reduced to one horrifying choice: kill – or be devoured!