He heard the sound of hurrying footsteps and ran towards them, only to find that it was a policeman attracted by the sound of shots.
The officer had met nobody.
"He must have gone the other way," said Tarling, and raced off in pursuit, without, however, coming up with his attacker.
Slowly he retraced his footsteps to where he had left the policeman searching the pavement for same clue which would identify the assailant of the night.
The constable was using a small electric lamp which he had taken from his pocket.
"Nothing here, sir," he said.

"Only this bit of red paper." Tarling took the small square of paper from the man's hand and examined it under the light of the lamp--a red square on which were written four words in Chinese: "He brought this trouble upon himself." It was the same inscription as had been found neatly folded in the waistcoat pocket of Thornton Lyne that morning he was discovered lying starkly dead..