'According to the locals, north of Northumbria is another kingdom called Pictland, or Pictavia depending on who you ask. If you seek allies or trade partners in these lands, you might want to travel to Perth, the capital of the Picts, and seek an audience with their king.'
As the dock is not unlocked yet, the hird must travel on foot towards the capital. When the party is about six hours from Perth, it will be ambushed by Grainne's party. Grianne will attempt to convince the party to be escorted to Caustantin, but the player may refuse that and attacks the Picts instead.
The battle, unless the party has eaccess to rank 5 skills and equipped with top tier equipment, is an one-sided battle in favour of the Picts. The battle may last two or three turns before an unavoidable defeat is the result.
Whether the party fought against Grianne or not, the hird will be escorted to king Caustantin mac Fergusa. In case the party fought against Grianne, the outcome of the conversation is the same as the compulsory or voluntary escort to Perth. When outside, the quest is finished and the succeeding quest will start immediately.