This quest begins after choosing to form an alliance with Grantebridgescire during The Alliance Map.
Find Magni in Duroliponte
When you’re ready, head southeast to Duroliponte in Grantebridgescire. There you will find a camp filled with warriors belonging to the Great Scattered Army, also known as the Great Summer Army. As you approach the ruins the soldiers will indicate that you will find their leader at the top. Ascend the stairs and when you reach the top, search for Magni’s Report (optional) for some context on the situation. It seems a battle was recently fought, and the Danes suffered heavy losses. Once you’ve had a look around, you’ll find Magni in the southeast of the ruins. He will explain what occurred in Grantebridge, and will ask you to find his leader, Soma.
Loot Wreckage and Meet Soma
Thankfully, Soma and the rest of the army aren’t too far away. They are just northeast of Duroliponte, on the shore of an island. You should take your longship and sail there from the coast of Duroliponte. This will allow you to pass by numerous sunken longships, which contain gold. Dive into the waters beneath the longships to find the gold before continuing northeast. As you approach the shore of the island, you’ll have the option to raid it. Do so and allow your crew to fight the enemies while you inspect the nearby longship, confirming that it belongs to Soma. Free the nearby Danes, help to defeat the enemies, loot what you can, and then head east to the nearby village of Middeltun, where you’ll find Soma.
After a brief cutscene you’ll have the opportunity to question Soma about Wigmund, a member of the Order of Ancients, and a bit more about the details of how she lost Grantebridge. When you’re done, the quest will complete.