"Lion's mane"

This is a rare story on behalf of Sherlock Holmes, not his biographer Dr. Watson. Holmes says that he left all business and went to rest at his house, which is located in Sussex. On the beach, the detective meets his friend Harold Stakehurst, who was the school principal. Stackhurst says he is waiting for Fitzroy McPherson, a school science teacher. A few minutes later, MacPherson appears in the d...