From the FFG website
A vast Chaos army is marching north, when suddenly the sprawling mass of bored and surly Orcs grinds to a halt because of yet another petty feud. In Chaos Marauders, each player takes control of one of the Orc clans involved, ready to show all the other mangy little creeps who’s boss of dis ‘ere scabby battle mob. You’ll stop at nothing to win. No amount of trickery will be low enough, no amount of thugish brutality too vile. Who knows, you may even get the mysterious Chaos Marauders on your side. Only one tribe can come out on top. Will it be yours?