The Imperium of Man, a vast expanse of space where the Administratum runs the lives of trillions of Imperial citizens. Here millions of soldiers are recruited daily to reinforce the Imperial Guard. Here the might of Adeptus Astartes guard their recruitment worlds. Here the Inquisition keeps a zealous watch for any hint of heresy. In this expanse the glory of mankind reigns and the xeno hordes are held at bay.
Beyond it's borders however is a different matter. Past the edges of the Imperium lie ancient ruins, horrors from the great beyond, and countless xeno hordes. But there are also relics of unimaginable worth, paradise worlds, and countless resources for the taking. Risk and reward both beyond measure for anyone brave or foolish enough to pass beyond the borders of the Imperium.
There are many who do. From the official crusades where countless men and machines are sent to expand the very borders themselves. To the shadowy hunts of Inquisitors pursuing malevolent forces. Regularly the Mechanicus launch great fleets into the void to find the wonders of ages past. But the most renowned of them all are the Rogue Traders. Empowered by their charters to be a law unto themselves they seek to pry the riches of the beyond from whatever forces might guard them.
Some Traders seek personal glory and wealth. Some seek to propel their families to greatness. Some are sent in exile. And some in honor. But no matter the cause they all seek their fortune beyond the edge.