Captain Bohseda will greet your party at the beginning of the Moddok Crevice mission. He will try to convince you to follow him and his band of Corsair Cutthroats.
Note that no matter which option you choose, the group will attack your party, but if you choose to follow him, eight Corsair Raiders will spawn as well.
"I cannot name my benefactor...only that he is very interested in seeing you reach Vabbi...alive. I want to keep him happy, and you want to line through this trip. So, what do you say? Can we trust one another?"