I am playing to The Road Darkens Saga. When the Uruk from Mordor is revealed, he makes an attack on the first player -- is he then returned to the staging area or does he stay engaged?

When enemies are instructed to make an immediate attack, they don't engage at all, they can attack from whatever zone they are currently in. Just resolve the section of the rules about enemy attacks (so declare a defender, etc) and leave the enemy where it is. Note that you should deal the enemy a shadow card for this immediate attack.

Thanks Nathan -- I was playing that incorrectly -- will try again!