The Pit-Prop Syndicate

From the Collins Crime Club archive, the third standalone novel by Freeman Wills Crofts, dubbed 'The King of Detective Story Writers'. Seymour Merriman's holiday in France comes to an abrupt halt when his motorcycle starts leaking petrol. Following a lorry to find fuel, he discovers that it belongs to an English company making timber pit-props for coal mines back home. His suspicions of illegal activity are aroused when he sees the exact same lorry with a different number plate - and confirmed later with the shocking discovery of a body.
What began as amateur detective work ends up as a job for Inspector Willis of Scotland Yard, a job requiring tenacity, ingenuity and guile .