Stories / The Return of Sherlock Holmes · 1904
The Adventure of Black Peter
A harpooned sea-captain and a sealskin tobacco pouch; Holmes spends a morning failing to spear a pig carcass and thereby frees an innocent man.
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⚠️ Spoilers below. The analysis discusses the solution, including who did it and how it's found out.
Summary & analysis
A retired whaling captain, hated and feared, is found pinned to his cabin wall with a harpoon through the chest; a young man is arrested on circumstantial grounds, and Holmes's opening experiment is a failed morning spent trying to harpoon a dead pig.
The harpoon test proves the killer was a trained whaler — no amateur drives one through a man and into wood. A sealskin tobacco pouch, a notebook of initials, and a night vigil at the cabin net a caller answering an advertisement Holmes planted for a harpooner.
Patrick Cairns killed 'Black Peter' Carey in self-defence over an old shared crime aboard the Sea Unicorn; the arrested young man was only after papers his father was cheated of. The strength-and-skill signature — one clean harpoon stroke — was the whole case.
Deeper reading
A grim, salt-stained case
Black Peter is one of the canon\'s harder-edged stories — a brutal sea-captain harpooned to a wall, a world of whalers and blackmail. Doyle opens with the memorable image of Holmes spending a morning failing to spear a pig carcass, an experiment that proves only a trained harpooner could have done the deed, and clears an innocent man in the process.
Method as exoneration
The heart of the story is Holmes using physical demonstration to overturn a wrong arrest — the experiment that shows what strength and skill the crime required. It is detection as public science, and a reminder that the canon\'s Holmes is as concerned with freeing the falsely accused as with catching the guilty.
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Techniques on display
Elimination
Striking out the impossible until the truth remains.
In this story: The framed young man cannot have the strength or skill the wound demands; eliminate him, advertise for the profession, and the real man walks in.
Observation
Reading occupation, history, and character from visible detail.
In this story: The wound is a résumé: only a whaler's arm sinks a harpoon through ribs into panelling, so the suspect pool is a trade, not a neighbourhood — Holmes proves it by failing at the pig.
Practise what this story preaches: every technique above links to a tool or game built on the same method. The best way to learn the canon is to reason along with it.