The Adventure of the Cardboard Box by Arthur Conan Doyle

A woman receives a grisly package containing two human ears, leading Holmes into a web of jealousy, betrayal, and revenge. The case connects to a tragic love triangle and an impulsive act of murder. The plot is grim and emotionally intense, dealing with domestic conflict and violent consequences. Originally considered too disturbing, the story was briefly excluded from some editions. It’s one of the darker, more psychological Holmes cases.