In Dangerous Freight Monsieur Vallon was a French farmer who lived in the Camargue near where a Douglas DC-3 carrying a gold shipment crashed. He was first on the scene of the crash and quickly rode into Arles to report the incident to the police. When the gold was missing from the crashed aircraft, Biggles ruled him out as a suspect because he couldn't have known that the cases on board the aircraft contained gold, and if he did, he would not have been in such a hurry to ride into Arles to report. At the time of the crash, however, Vallon had a lodger, one Monsieur Laroux, a tourist who was staying at the farm because his car had broken down. Laroux stayed at the crash site while Vallon rode to Arles and so Biggles' suspicions fell on him instead.