Pseudo-Poll - A Bullet to the Head

So, let's say you have the following situation.  A character has a gun to the forehead of another character.  The 'victim' either chooses not to, or is incapable of resisting.  The trigger is pulled from a distance of zero inches, but not enough pressure is applied to trigger the safety.

There is no chance of a miss.  There is no chance of the person dodging.  The angle of the shot is such that a deflection is impossible.  The 'victim' has no supernatural powers, armor, or anything else.  Any Compels will be refused, so no 'last minute backup' to save them.

What happens?  Do you engage mechanics at this point, and if so, which mechanics?