I'm looking for a series that is 1 season and 18 episod it's and it starts whit A or P or S or N (ldk)

I’m looking for a live-action series that has 1 season and 18 episodes. It is in English, made in America, and starts with the letters A, P, S, or N.

One of my friends watched a series and said it was so dark that it mentally affected him. However, he won’t tell me the name of it, what it’s about, its genre, or when it was made. Do you have any idea what it could be?

Please help—I can’t sleep at night!