This chapter is a complete guide for City of The Sun quest. Here you can find tips that will help you to finish this quest in the most beneficial way.
The quest starts when you enter Daytower. Your goal is to find Olin and get all possible information about his connection to the cultists. First, you must get to Meridian city.
There, you must meet with Erend. Follow the quest marker. When you get to the place you will see a cut-scene. Next, you must speak with Erend. Finally, the man leads you to Olin's house which you must search trough.
When you are in the house, use Focus and check the floor on the ground level. You can find the door that leads to the basement. Sadly, you don't have a key that could open them. Go to the floor and, from there, use a ladder that allows you to reach the highest level of the building. There, you can find metal bars that you can push off to destroy the gates. Go down and enter the basement.
On the left from the entrance you can find a hologram. Scan it by using Focus and you will see a short cut-scene. Additionally, you will find Olin's journal. Take it to proceed further in the quest. After reading it, use Focus on the map hanging on the wall. Use interaction button.
After all that, speak with Erend. Explain to him that Focus allows you to see more details and he asks you to help him to find his sister's killers. A new quest appears in your journal - The Field of the Fallen. The guide for that quest is in dedicated chapter.
To proceed, you must go to the place where Olin currently stays. Use the campfire that is the closest to your destination point, then find a mount and stay on the road. When you start to get closer to the place where Olin is you can come across small groups of cultists. Try to eliminate them without alarming other enemies.
Climb on the place shown on the picture and go in the direction pointed by the marker. You must watch a short cut-scene during which you can learn that Focus stopped working. Your goal is to eliminate all cultists and Corrupters that accompany them.
Use the ladders to get on the upper level of the excavation site. There, you can stealthy eliminate a few cultists. When Olin learns that you are alive, he will help you. However, he is not very resistant so the burden of the fight rests on your shoulders. The best way to deal with Corrupters is to burn them.
After the fight, speak with Olin. The conversation makes the story more clear. At the end of the conversation you can decide on Olin's fate. Regardless of your choice, the quest is finished and a new one takes its place - The Field of the Fallen.