Stories / His Last Bow · 1911
The Adventure of the Red Circle
A lodger who never shows a face communicates by candle flashes; Holmes reads the window code and walks into a secret-society vendetta.
✅ Public domain — read, share, and adapt freely.
⚠️ Spoilers below. The analysis discusses the solution, including who did it and how it's found out.
The Adventure of the Red Circle summary & analysis
A landlady is unnerved by a lodger who never shows a face, communicates by printed notes, and demands meals left at the door; Holmes takes the small mystery of the invisible tenant.
Holmes watches the house and reads a candle flashing at a facing window — signalling in code, letters counted by flashes. The lodger is a woman hidden by her own protector; the flashes spell danger and a name, and a secret-society vendetta closes in.
The Red Circle — an Italian criminal brotherhood — hunts the couple across the Atlantic; a Pinkerton agent and a timely shooting end the pursuer. The unseen lodger's whole ordeal was written in flashes across a courtyard, waiting to be read.
Deeper reading
Signals in the dark
The Red Circle builds a small domestic puzzle — a lodger who never shows her face — into a transatlantic vendetta, decoded through candle-flashes counted into letters across a courtyard. Doyle enjoys the mechanics of covert signalling, and the ordinary boarding house opening onto a secret-society killing is a satisfying widening of scale.
The society that follows you
Behind the case stands the Red Circle, a Neapolitan brotherhood whose reach follows emigrants across the ocean — the canon\'s template for the vendetta that cannot be outrun. An American Pinkerton agent already on the hunt gives the story, like The Valley of Fear, an international law-enforcement dimension.
Play this story
Free, built on this case's own facts — no sign-up, nothing to install.
Porlock's Book Cipher
Encode and decode book ciphers with word numbers, watch Holmes crack Porlock's Valley of Fear message, and try the Gloria Scott and Red Circle codes.
Open the tool →The Candle at the Window
Read the flash-code exactly as Holmes read it across Howe Street.
Play the game →The Red Circle Flash-Lamp
Write and read candle-flash messages with the code of the Howe Street window.
Open the tool →Techniques on display
Ciphers & codes
Secret writing broken by frequency and pattern.
In this story: Candle-flash signalling decoded by counting: flashes grouped into letters (one for A, and so on) turn a flickering window into sentences of warning.
Practise: 💃 Dancing Men Cipher Bureau Practise: 📖 Porlock's Book Cipher Practise: ⏱️ Cipher Sprint
Observation
Reading occupation, history, and character from visible detail.
In this story: The lodger's habits — printed notes, a woman's cigarette, meals for one — tell Holmes the hidden tenant's sex and situation before she is ever glimpsed.
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.