Daervunn the Ranger was detained by the Rohirrim at the Ford of Isen when he attempted to warn them of Saruman's treachery. It appears that some faction within the Golden Halls of Edoras has a grudge against the Dúnedain and has ensured that their passage through the region will not be easy.
'${PLAYER}! Well met... or so I would say were I not bound to a post. I came here to warn Théodred of Saruman's schemes, but I am afraid the Wizard remains a step ahead of us.
'One of Grimbold's men produced a message from Edoras ordering the detainment of any Men of Dúnadan descent. It seems that Isengard may have wormed its tendrils into the nobility, if I do not miss my guess.
'Now, as much as I enjoy the comforts of a cheery camp-fire and the good company of my guards, I do not suppose you could see fit to speak on my behalf with the camp commander? I suppose I might be able to free myself, but I would likely injure or kill some of Grimbold's men in the process, and I would rather not give credence to Saruman's claims against us.'
Grimbold is at the Ford of Isen.
Daervunn has asked you to speak with Grimbold on his behalf.
Grimbold has outlined his suspicions about Isengard's involvement in the orders he has received. You must find some way to free the Ranger without Grimbold's direct involvement.