Oh, i really love this adventure site.
My campaign will start just right there. The charakters will find themself in cages as slaves, some of them for labour, other for pleasure or death rites, departed by races and classes. Then comes an antagonist, perhaps a high ranking rust brother, and an auction will happen. The charakters aren´t sold and shall be killed, but the buyer has a heart, buy them and make a slave hunt with them, giving the last slave captured the opportunity to live as a labour or pleasure slave.
So, the new formt group will be busy to survive with a rust brother, iron guards, the demon dogs and slavers on their trail ...