The Spark is the final side quest in the Kuttenberg Hole in the Wall guild storyline. After Via Argentum and The Thieves' Code, the guild recruits you for a sabotage mission: collapsing a major silver mine with black powder to hurt Sigismund's production.
The Spark and the task Civic Duty (
Civic Duty) cannot both be completed. Finishing one fails the other. This quest is your last chance to begin Civic Duty if you still want to snitch. This article follows the standard Spark path. For betraying the guild, see the Civic Duty guide.
How to start The Spark
You need Via Argentum (
Via Argentum) and The Thieves' Code (The Thieves' Code) finished. After a few in-game days, a Messenger of the Guild appears as a random event while fast traveling. Talk to him; he sends you to Chenyek at the 
Hole in the Wall tavern.
Decision: Knuckles or Chenyek
As in earlier guild beats, Knuckles may offer an alternative: murder Chenyek so Knuckles can take over. The main cast shuffles, but this remains the last quest in the line, so you will not see big follow-up differences either way. This path pays less and is not recommended if you want the best ending and reward.
Phase 1: obtaining the black powder
After the messenger, return to Hole in the Wall and speak with Chenyek. Your job is to destroy the mine near Horschan, which means sourcing explosives first.
Gunsmith Prokop Eldris works just south of the tavern. Chenyek gives you 100 Groschen toward powder. Ask Eldris about a shipment: pass a skill check (Intimidation is the easiest route but costs reputation) or bribe him for the lead.
The shipment: go north of Bohunowitz toward the river. If Bohunowitz fast travel is still locked, Devil's Den is a close alternative.
You will find Whisker and his crew with a stuck cart.
Pass a Charisma check to get cooperation (and some reputation) or simply buy the black powder. He gives a key; loot the Black Powder Keg from the chest by the cart.
Phase 2: destroying the mine
Go to the Horschan mine (the same site from Via Argentum), southwest of Grund. Meet Goliath and the other guildsmen at the campfire east of the road. Optional dialogue with Hog; Goliath moves the quest forward.
You must wait until nightfall (you can skip time with him), roughly 10:30 PM. After his briefing, other members leave to light fires as a distraction while you and Goliath approach the mine. Only Henry enters, plants the keg, lights the fuse, and sprints out.
Goliath starts walking toward the mine. Follow him.
At the mine entrance with Goliath, do not go in yet. Drink 
Saviour Schnapps so you can reload this moment later.
Kill Goliath. The quest fails, but you keep the Black Powder Keg.
Return to the guild campfire and use the contextual action Throw the barrel into the fire. You get a Game Over screen and unlock 
Remember, Remember…. Reload your Schnapps save at the mine entrance and continue the quest for real.
Phase 3: in the mines
Enter the mine, follow the path to a crossroads, turn right, take ladders to the lowest level, and find the support beam marked with a reddish rag. Place the barrel there.
Lighting the fuse needs a torch. After it is lit, you have about two minutes to escape.
On the way out the blast knocks Henry out.
You wake to learn Goliath pulled you clear. Soon six soldiers try to arrest you.
You can fight (hard), flee, or pass a tough Intimidation check. Expect lower Charisma while you are covered in soot and dirt.
Return to Hole in the Wall. If you stayed loyal to Chenyek, you learn Knuckles tried to sell you to the guards and the guild dealt with him.
Rewards
- Side with Chenyek: 150 Groschen and a final toast with the guild.
- Side with Knuckles: 60 Groschen.
Finishing the quest closes the Kuttenberg guild storyline. The tavern stays open as usual.
The Spark FAQ
Are The Spark and Civic Duty compatible?
No. Complete one and the other fails. Pick a path and use saves if you want to see both.
Why am I not getting the messenger?
Ensure Via Argentum and The Thieves' Code are done, then pass a few days and keep fast traveling until the random encounter fires.
Knuckles or Chenyek?
Chenyek is the better outcome: more money and toast scene. Knuckles pays less and involves killing Chenyek.
Where is Whisker's cart?
North of Bohunowitz on the river. Use Devil's Den if Bohunowitz is not unlocked.
How exactly do I earn Remember, Remember…?
Save at the mine mouth, kill Goliath, return to campfire, throw the barrel into the fire, watch the game over, reload the save, then complete the mission normally.
What if soldiers surround me?
Fight, run, or Intimidation. Charisma options suffer because you are filthy from the mine.