Based on Stephen King's 2014 book, Mr. Mercedes follows a demented killer who taunts a retired police detective with a series of lurid letters and emails, forcing the ex-cop to undertake a private, and potentially felonious, crusade to bring the killer to justice before he is able to strike again.
This is described as a grounded character-driven drama based on Wolitzer's novel about a group of friends who meet at an arts camp when they're 15 in 1974. The series chronicles their relationships throughout the next three decades dealing with the great expectations of youth juxtaposed with the realities life hands you as you get older.