The key is in your hand and the circle behind you is broken, and through the library door Mrs Marsh is calling for silence: the knocking has started again, and it is coming from two directions at once.

Mark Two: The Knocks on the East Wall

Back at the table the circle has closed again without you, and Sir Arthur Conan Doyle is writing in a notebook by the light of the red lamp. He was a doctor before he was a writer, he tells you in a whisper, and a doctor writes everything down: every run of knocks, the minute it came, and where everybody in the room was at the time.

Mrs Marsh says the spirits knock on the old alphabet, with a pause between letters, and that tonight they are spelling the boy's name. The knocks come out of the walls, and in the dark nobody can say which wall. Her nephew Cyril, who came down from London with her, was not at dinner and is not at the table.

Sir Arthur's notes:

TIME  KNOCKS     CYRIL
9.02  11 9 20    not seen
9.04  16 8 15    not seen
9.05  5 2 5      not seen
9.09  11 9 20    not seen
9.12  16 8 15    in doorway
9.13  5 2 5      in doorway

At twelve minutes past nine Cyril came in with his aunt's shawl and stood in the doorway in plain sight, both hands full, until a quarter past. Mrs Marsh says the spirits are spelling the boy's name tonight, and louder than she has ever known them.

Sir Arthur taps his notebook with his pencil. Holmes, he says, would ask which of these knocks the young man could not have made.

Read what the house is knocking: the knocks nobody in the room could have made.