The German's Treasure is a Kuttenberg Guild task in Kingdom Come: Deliverance 2 that follows Beyond the Grave (walkthrough: Sedletz dual guide). Rat orders you to rob Beikovetz, innkeeper of the All Saints Tavern, and humiliate a Sigismund loyalist. This walkthrough uses the easiest Kuttenberg Underground approach so you skip most of the public tavern.
Infiltrate the All Saints basement
Your goal is the basement under All Saints Tavern, near the large church in southern Kuttenberg.
You can bluff or sneak through the tavern itself, but the quietest path is the Kuttenberg Underground tunnel network.
Underground map
Our overview marks the tavern with a beer icon and places the recommended starting point southwest along the river, outside the walls.
Best underground entrance
Entry: follow the river south of Kuttenberg and enter the mine mouth with water pouring out.
The same spot on the overview map:
At the first crossroads, keep moving straight against the current. Push through the flooded section until you reach a barricade with a side tunnel to the left. Follow it to the 
Wasteyard interesting site.
Grab stray Groschen and trinkets if you like, then continue through the tunnel that has a wooden floor. It leads to Underground Crossroads, lit by a standing torch. Expect roughly 90 Groschen, plenty of coal, and other loose loot.
Climb the ladder, move forward in a straight line, and you will reach a wooden door (Medium lock) that opens into the All Saints Tavern basement.
If your stealth or lockpicking is shaky, this is a good moment for Saviour Schnapps, Nighthawk, and a Quickfinger potion.
Phase 2: Finding the treasure
Prefer night infiltration. During the day, miners sit right beside the door. After dark they sleep. Do not knock them out: companions wake fast. Crouch and route around them instead.
You only need two side rooms. Skip the large chamber with two sleeping miners unless you want extra scouting.
All quest items to retrieve
The chest: in the first chamber just past the door, open the Hard locked chest for the Bloodied Wedding Dress.
The hidden wall: enter the small room on the right. Inspect the loose brick patch (same idea as the Sedletz secret wall in Beyond the Grave, full guide). Inside you find an Old Rusty Sword, Footpad's Hideout Map, and Old Hideout Map.
The metal chest: still in that room, the Very Hard locked chest holds an Old Painted Statuette, a skill book, and high-value Farkle badges.
When the objective list is clear, exfiltrate through the tavern stairs or double back through the tunnels.
Rewards and how to sell
The haul is mostly blackmail fuel against Beikovetz, not showroom loot. Rat wants proof, but your payout comes from a fence outside the walls.
Travel to the tavern just west of Kuttenberg (the same homestead where Menhard can wind up banished). Find Innkeeper Helga, usually working around the bathhouse.
Password: when she asks, answer with “I'll have a big-eyed monkey.”
Her first offer is low. Pass a Speech check to argue real value, then haggle. You can land around 250 Groschen without much trouble. That concludes The German's Treasure.
The German's Treasure FAQ
Do I need Into the Underworld?
No. This route is self-contained once you know the river entrance and the ladder sequence.
What if I fail the Medium door?
Save with Saviour Schnapps, stack Quickfinger, and retry. The public tavern route remains a noisy fallback.
What if miners spot me?
Pop Saviour Schnapps before you commit, try a later hour, and stick to shadows. Combat in the bunk room ripples to every sleeper.
Prerequisite tasks?
Finish Beyond the Grave, then ask Rat at the Hole in the Wall for more work (dual guide).