The Mercies of Knowledge

 is a Stranger mission in Red Dead Redemption II. The quest becomes available during Chapter 4.

Story
Professor Andrew Bell III approaches the protagonist and asks him if he knows where he can find any moonshine. He claims the liquor is not for drinking and will be used for a 'machine of love'. He promises to pay if some can be brought to him. After visiting Alden, the Train Station Clerk in Rhodes. He gives the protagonist a hot tip on where to find some.

A transport of moonshine is heading into Saint Denis from the north and there is a big opportunity to intercept the shipment. Once you pass the wooden bridge outside of city, the cart will arrive with two riders alongside two riders on horseback. After taking out all of the guards, the cart is delivered to the professor.