Red Dead Redemption Undead Nightmare Episode 3: A Cure for Most of What Ails You

"Nigel West Dickens is selling his tonic to the residents of Fort Mercer when John Marston interrupts him and is disgusted at Dickens selling it to the miserable people for 100 gold coins, forcing Dickens to give to the people for free."
"Marston finds D.S. MacKenna in a tent in Plainview with his camera and a hogtied zombie. MacKenna tells John about his dream of making a movie about the zombies and asks John to capture a Retcher for his film."
"Inside Fort Mercer, Marston encounters the American Army Captain putting up a poster. Thinking that the captain has been given the work of underlings, Marston jokes with him about it. The captain rounds on John, tersely pointing out that the posters are of people who are missing throughout the frontier and need to be found before they meet a grisly fate. Seeing that it is not a laughing matter, John decides to help rescue the missing person."