What happened in the end of chapter 8 in Artemis fowl book 1?

Butler speaks to the troll in a calm, soothing voice. Butler rams the mace under the troll's tusks. Butler retreats to the other side of the hall and the troll goes after him. Butler turns to the troll, shooting it in between the eyes. The shots do not kill the troll for it has a thick forehead, but they do cause an instant concussion. It falls to the floor and Butler hurries after it. Butler gives the troll several crippling blows. When he gets ready to shoot it again, Holly asks him to stop and let the troll go, telling him that he owes her one. Butler drags the unconscious troll to the armored trolley and heaves it into the night.