Isengard is littered with strange devices which have some role in Saruman's preparations for war. These machines are frequently maintained by goblins or by human apprentices who have been trained in their operation by Saruman.
'I have spotted a number of strangely-robed Men wandering about, occasionally tending to those devices.
'They are some sort of apprentices in Saruman's service. Without them, he will have more trouble running Isengard. Will you see if you cannot deal with a few of them quietly?'
Saruman's apprentices can be found in Isengard.
Dagoras has asked to you to hunt down any of Saruman's apprentices that you come across in Isengard.
Dagoras is within the Ring of Isengard.
You should return to Dagoras with news of your success.