The Adventure of the Lion’s Mane by Arthur Conan Doyle

Told by Holmes himself, now in retirement on the Sussex coast, this case involves a man found dying with mysterious lash-like marks on his back. As Holmes investigates, he uncovers the presence of a rare and deadly marine creature: the lion’s mane jellyfish. The plot is one of natural danger rather than human crime. It emphasizes Holmes’s observational powers and independence. A unique and atmospheric mystery with a scientific twist.