This page offers a guide on how to complete and where to locate The Puppeteer, which is a mystery located in Sciropescire, AC Valhalla.
Talk to the Dead Body
This mystery is located just west of Wenlocan Abbey. When you approach the body it’ll tell you it needs silver to cross over to the afterlife. Of course, this is a hoax, and there’s actually a man behind the locked door. Eivor is not particularly amused by such fraudulent behaviour, and to complete this mystery you’ll need to find a way into the man’s cave and kill him.
If you head up the cliff, you’ll find a house just north of the mystery marker. Then, when you’re inside the house you’ll need to move the moveable shelf to reveal a hole that heads down underground. Continue along the underground tunnel until you reach the man, then kill him to complete the quest. You can loot the area for a couple valuables and silver pieces.