“The changing of the numbers,” Willis repeated. “At least, it looks like that to me. No. 1 does the Monday run to the distillery. They change the number plate, and No. 4 does it on Wednesday, while No. 1 runs to some other establishment, where it can be freely examined by anyone who is interested. How does it strike you?”
“You have got it. You have certainly got it.” Laroche was more enthusiastic than the inspector had before seen him. “It’s what you call a cute scheme, quite on par with the rest of the business. They didn’t leave much to chance, these! And yet it was this very precaution that gave them away.”
“No doubt, but that was an accident.”
“You can’t,” said the Frenchman sententiously, “make anything completely watertight.”
The next night they went out to the clearing, and as soon as it was dark once more entered the shed. There with more powder—white this time-they tested the tank lorry for finger-marks. As they had hoped, there were several on the secret fittings, among others a clear print of a left thumb on the rivet head of the spring.
A moment’s examination only was necessary. The prints were those of M. Pierre Raymond.
Once again Inspector Willis felt that he ought to have completed his case, and once again second thoughts showed him that he was as far away from that desired end as ever. He had been trying to find accomplices in the murder of Coburn, and by a curious perversity, instead of finding them he had bit by bit solved the mystery of the Pit-Prop Syndicate. He had shown, firstly, that they were smuggling brandy, and, secondly, how they were doing it. For that he would no doubt get a reward, but such was not his aim. What he wanted was to complete his own case and get the approval of his own superiors and bring promotion nearer. And in this he had failed.
For hours he pondered over the problem, then suddenly an idea which seemed promising flashed into his mind. He thought it over with the utmost care, and finally decided that in the absence of something better he must try it.
In the morning the two men travelled to Paris, and Willis, there taking leave of his colleague, crossed to London, and an hour later was with his chief at the Yard.