Get the Tattooed Head from the entrance to the Alliance compound.
Here's the deal, mate: to protect me treasure map, I tattooed it onto me first mate's scalp.
Of course, he's dead now, along with most of me crew. The Alliance doesn't even know what they have - his severed head is hanging from a tree at the entrance to this camp.
Grab that head and take it to Gazlowe back in Ratchet.