This page of the Assassin's Creed Valhalla guide has a detailed walkthrough for the Twists and Turns mission.
Eivor managed to solve Birstan's and Estrid's problem. The woman will soon return safely to her native France and Birstan was given a second chance to make a life with Alfida. It is time to form an alliance with Birstan.
Rewards: 5100 XP.
Find and speak to Birstan
You will find Birstan in a small hunting camp just outside Colchester. The man will invite you for a hunt. Follow him.
You have to hunt and kill 5 wild boars to fill the mission progress bar to 100%. You will find a whole herd of boars near the water. After the hunt, talk to Birstan.
Join Birstan and Alfida
Return to the city (it is best to use the fast travel option) and go to the ealdorman's estate.
There will be an argument with Eluric. As it turns out, Estrid didn't tell Birstan that she has a child, and Eluric is his son. On top of that, King Aelfred's men found Lady Estrid and are on their way to rescue her.
Speak to Rollo
You will find Rollo in a camp by the river. He is preparing for an expedition to France and is unaware of the incoming danger.
Defeat the Saxons
After a while, the king's men will appear – you have to fight them. There are several elite leaders among the soldiers. Beat all Saxons.
When it's over, talk to Estrid. The woman will sail safely to France – this will complete the mission. As a reward, you will receive 5,100 XP.
If you chose the wrong traitor during the Old Wounds mission, Gerhild will show up at the camp with the soldiers and try to harm Estrid. When the soldiers start shooting, one of the arrows will hit Estrid. in the side The woman will be seriously injured but she will survive.