LEGO: Kingdoms - Escape from the Dragon's Prison - 7187

Help the king's knight escape! One of the king's knights is being held captive in the tower by the evil dragon knights! Another king's knight is here to help and smashes through the prison gate with his ballista. Help him avoid the crashing boulders being hurled his way from the tower gate catapult! Then defeat the dragon knight on horseback to escape!