Suddenly he tapped loudly and sharply: No. 380 PASS IT ON. Rubashov sat up quickly. He understood: the news had been tapped on through eleven cells, by the neighbours of No. 380. The occupants of the cells between 380 and 402 formed an acoustic relay through darkness and silence. They were defenceless, locked within their four walls; this was their form of solidarity.
Arthur Koestler, Darkness at Noon, Modern Library, New York, p. 138.
PLACE: A prison, Russia.