This quest begins once you have pledged to Lunden from the Alliance Map in your longhouse at Ravensthorpe. You should begin by travelling there and approach from the north toward the Cripple Gate. When you approach the gates a cutscene will trigger, during which you’re introduced to Stowe.
Note: Soon after the cutscene, you’ll have an opportunity to pursue a romance with Stowe if you want to. Just choose any option with a heart before it.
After the initial cutscene you’ll need to help Stowe in a fist fight. After the fight, go through the dialogue options as you please, and then follow Stowe through Lunden. When you reach the Governor’s Villa, Stowe will note that something is wrong. Follow him inside to another cutscene, during which you’ll meet Erke.
Investigate Tryggr’s Murder
Now that you’ve been unable to meet Tryggr due to his untimely death, you’re tasked with helping to investigate exactly what lead to his demise. You should begin by examining his body on the chair. Next, head toward the entrance to the north and examine the floor here. Now turn west and destroy the crates in the corner of the room, allowing you to investigate the contents. Finally, turn your attention to the ceiling, where you’ll find a body hanging from it. Inspect this and then jump down to trigger a cutscene.
Infiltrate the Temple of Mithras
When the cutscene ends, you’ll be tasked with investigating the nearby Temple of Mithras. This can be found to the east of the Governor’s Villa. You can travel over the rooftops and use the rope system to approach the temple from stealth. The temple is heavily guarded, so you’ll need to be careful here. Use your raven and Odin’s Sight to get an idea of where the guards are located. If you don’t want to be attacked on sight, keep your cloak on to ensure that guards will investigate before attacking when you’re spotted.
Take out the guards in the temple grounds as you see fit, then enter down the steps at the centre of the ruins. You’ll pass through a crack in the wall, and once inside you’ll have access to a wealth of evidence. Use Odin’s Sight to highlight all the points of interest, and inspect each one as you go, including a couple of letters and some surgeons tools. You’ll then need to move the barricade on the southern wall to the right, in order to gain access through the hole in the wall behind it.
Once you’re through the hole, continue down the steps to the south and then west through the ruins. You’ll eventually come to a dead end (at least one the ground floor) where you find a chest which contains the unique Briton Shield. With the shield looted, look above you to the north and break the wooden barricade with an arrow or torch. Climb up the wall and go through the evidence in this room, after which you’ll have all that you need and can return to Stowe and Erke at the Governor’s Villa. You can leave the ruins the way you came or by the locked door in this room.
When you return to Stowe and Erke, go through the motions of dialogue as you wish. When the cutscene ends, the quest will be complete.