Talk to Terrance in Britain and he'll tell you about the Resistance. If you agree with him, he'll tell you to speak to the owner of the "Arms of Justice": this is Chamfort of Yew, who will accept you in the Resistance and tell you to go talk to the local leader, Landon. He will tell you about the Crown of Lord British, and suggest you to talk to Sir Simon, who is hiding in Bordermarch.
Still in Yew, a prisoner named Greymarch will ask you about his son, Froed. If you met him in Skara Brae, Greymarch will be relieved and thank you by telling you about Lord British's Sceptre, and to ask about it to Sir Simon of Bordermarch.
Shall we go to Bordermarch straight away, then? No. Let's go to North Britanny instead, where a farmer named Thentis is a member of the Resistance. He'll give you an appointment at the well at midnight. Talk with the other members of the Resistance, Vigil, Joshua and Leof and learn more about the Shadowlords. They will relay you to Sir Sean of the Lycaeum and to Sutek, who lives on a small island in the South.