From the back of the adventure:
"Tastes Like Chicken!
At least that's what they say about flesh of a kind you've never tasted before (and we sincerely hope your heroes haven't). Of course, there are plenty of folks in the City of Lost Angels who have been reduced to such horrors. You'd better pray for your heroes, because that's exactly where they're headed.
Once in LA, the heroes are charged with trying something no one in their right mind would attempt. The jewel they're looking for-the fabled Heart of Darkness itself-is apparently on Rock Island, the impenetrable fortress prison sitting in the heart of shark-infested Prosperity Bay. It's up to them to make a desperate attempt to actually break into the prison, and there are more than just a few greenbacks on the line.
Heart o' Darkness is the second in the world-rocking Devils Tower trilogy of adventures. Even if the heroes managed to get this far, they can't afford to fail now because-whether they know it or not-the fate of the city and everyone in it hangs in the balance."