Man episode 6 hits you in the gut (Spoilers)
Mainly because we spend the first chunk of the episode with the victim, getting to know him, seeing him born, growing up, dealing with his disability, hanging out with his friends his family, showing us his aspirations and dreams.
Its a good while before we even see Dahmer, but by the time you do you're pretty invested in Tony and care about him, which makes him meeting Dahmer that much more tense and depressing to watch.
They show Dahmer actually liking him though at first, not drugging him, and legit trying to have a relationship with him, you almost have hope Dahmer doesn't kill him. But when it just cuts away and we see Tony's mom saying he's missing its like a sledgehammer to the gut. Then seeing Tony laying dead on his mattress like the others just hits you really hard. Then we see Dahmer eating one of his organs, just such a dark depressing gut punching ending.
Really great episode, giving us so much time with Tony at the beginning was a brilliant decision to just further make us feel just how fucking evil Dahmer was and the lives and dreams these guys had before meeting Dahmer and he just snuffed them out.