He looked out, astonished, and saw by the white enamelled walks twenty feet from the window that they were already in the tunnel.

The stoppage might arise from many causes, and he was not greatly excited, nor did it seem that others in the carriage took it very seriously; he could hear, after a moment's silence, the talking recommence beyond the partition.
Then there came, echoed by the walls, the sound of shouting from far away, mingled with hoots and chords; it grew louder.

The talking in the carriage stopped.

He heard a window thrown up, and the next instant a car tore past, going back to the station although on the down line.

This must be looked into, thought Percy: something certainly was happening; so he got up and went across the empty compartment to the further window.