Three members of the Triads are arrested close to the camp. They are on their way to a rendez-vous at the barbed wire - probably to recieve information to be transmitted outside Hong Kong.
They are accused of being in a forbidden area, but, in spite of torture, they refuse to reveal the purpose of their mission before they are executed.
Source:
F. W. Shaftain's Memoirs, p. 5 at https://drive.google.com/file/d/1IFHSG5WKSSBn1fPQJQueH53-UWiThFYP/view