Red Dead Redemption 2's story mode features a series of optional missions called Stranger missions, where some often-colorful characters will ask Arthur for help in completing several different tasks. The Mercies of Knowledge is among the shortest Stranger missions to complete.
The Mercies of Knowledge is available right after completing The Joys of Civilization story mission at the beginning of Chapter 4. To begin the mission, you must speak with the man located in the northern part of Saint Denis, near the river bank. Once close, the location of the stranger will be marked on the map.
After speaking with him, he will introduce himself as a professor and ask Arthur if he could bring a lot of moonshine for scientific purposes. Arthur isn't particularly convinced that it's for science, but he will help the professor nonetheless.
After completing the first part of the mission, head over to the train station in Rhodes to speak with Alden, who will provide information about a big moonshine delivery, which will be entering Saint Denis shortly after.
Once you are done talking with Alden, you must intercept the moonshine wagon before it enters Sant Denis. Head to the location marked on the map and wait a short while for the wagon to appear. You can either ride alongside it to throw the drivers off or just kill them with any weapon you prefer. As the area is usually deserted, killing them is the fastest way to go.
After the wagon has been stolen, it's time to bring it to the professor, who will then reveal why he needed so much moonshine.
The professor needed all that moonshine to build a working electric chair, which is meant to make executions more "humane". He is planning a big public demonstration, but he still has to find a volunteer and obtain a permit to perform the execution.
The professor will ask Arthur for help with both. First, it's time to get the permit, so head over to the Saint Denis police station to get it from the chief. The man is open to the idea, but only if his price is met. The base price is $100, but it's possible to pay a little less by haggling.
After obtaining the permit, head back to the professor. He has found the perfect candidate for the execution, a dangerous criminal called Wilson McDaniels. The man is wanted dead or alive, so no one will bat an eye if he is killed with the electric chair. The professor will hand out the wanted poster to Arthur, who will have to capture the man alive.
Wilson McDaniels is located in the New Hanover region, in an area right to the north of the "N" in Hanover on the map. Once in the area, the man will make it clear that he has no intention of beingcaptured, and . Kill all of the enemies, and start chasing McDaniels: whip out the lasso and use it on the man when the reticle turns red. Once McDaniels has been captured, bring him back to the professor in Saint Denis.
During the seventh and final part of the mission, you will be able to check out the public execution for yourself. Things, however, don't go as well as the professor planned, as the electric chair is not powerful enough to kill a man quickly. He won't have another chance to perfect it, as he will also die during the ensuing events.
After the execution is done, The Mercies of Knowledge mission will be complete.