You are part of the crew of the Jailhouse Rock, a proud member of the Space Brigade.  While you're here on Earth, you've infiltrated the strange group known as the Followers of Set.  Amazingly evil dudes, who clearly have to be stopped -- if they succeed in taking over the Earth, they'll probably manage to conquer more than that.  You're keeping an eye on them, and should report in sometime soon.  You'd better do so subtly, though -- there is little question that, if they knew you were a spy, they would kill you...