King Coal by Upton Sinclair

Hal found Jerry Minetti with the two officials in their hotel-room: Jim Moylan, district secretary, a long, towering Irish boy, black-eyed and black-haired, quick and sensitive, the sort of person one trusted and liked at the first moment; and Johann Hartman, local president, a grey-haired miner of German birth, reserved and slow-spoken, evidently a man of much strength, both physical and moral. He had need of it, anyone could realise, having charge of a union headquarters in the heart of this "Empire of Raymond"!

Hal first told of the kidnapping of the committee. This did not surprise the officials, he found; it was the thing the companies regularly did when there was threat of rebellion in the camps. That was why efforts to organise openly were so utterly hopeless. There was no chance for anything but a secret propaganda, maintained until every camp had the nucleus of an organisation.