This story could go anywhere. I mentioned the faceless hunters riding giant vampire bats as being a possible menace, but the mysterious "conspiracy" could send other strange things after the team as well. Just play it by ear. The only stipulation is that I don't want the conspiracy to be uncovered in this story. I see it as an ongoing, behind-the-scenes threat to the whole team that could go on indefinitely. It's a conspiracy that's like an onion--even if one layer is uncovered, there are several others beneath. And whoever is at the very bottom of it...I have no clue.
