He's British, of Course

 is a Stranger mission in Red Dead Redemption II. The quest becomes available after Chapter 2. There are five parts to this mission

Story
Arthur can find a crashed caravan of circus-members in the state of Lemoyne. There is a lost sad man sitting around. He says that he is a female animal wrestler by the name of Margaret and his beasts escaped. Without any animals, his show is no longer a show and he asks us to find his lost Zebra, Tiger and Lion. Those should be easy to spot in these regions.

Walkthrough
After meeting with Máximo, decline his first offer of $10 for the map for him to lower the price to $5. If you scared him away, robbed or killed him by accident, you can buy his map from any fence in the game.