A scout has encountered Gandalf while riding in the Westemnet, and the wizard mentioned that he wishes to speak with you.
'Oh! Are you that ${PLAYER} I've been hearing about? Gandalf Greyhame wishes to speak with you. I believe he said he would be stopping over briefly in Edoras.
'Perhaps you will find him there, if you ride hard! I believe he was hoping you would help the folk of the Eastfold.'
Gandalf can be found near the main gate of Edoras.
You should hasten to Edoras to begin helping the people of the Eastfold.