This is where everyone turns to me and asks "Why are we killing each other?"  And most of them won't accept "Because it's fun," So I came up with a little history.
   The world is exactly as it is.  Several Major Corporations are vying for lucrative government  contracts.  The assassins are going to kill major other corporate leaders if they are not stopped by other assassins first.  The Corporations all know that the assassins are just getting started and the final assassinations will not take place for another year, so they are all launching preemptive strikes against each other.  Only Mr. Johnson (the GM) knows who your targets are.  Mr. Johnson is your only link to your corporation that is feeding you and paying you a hefty sum to risk your neck.  You want to find out who your target was going to kill for two reasons: #1, They could be your assassin, #2 They are a threat to your company, a threat that Mr. Johnson will pay to have eliminated.  Your orders are simple.  Kill your target, stay alive and undetected, kill any other targets of opportunity. (Stupid Out-Of-Character note, obviously bystanders are *Not* targets of opportunity, witnesses and innocent deaths are to be avoided at all costs, for secrecy's sake)