"I know it wasn't any good by itself. But it was a clue. Nobody saw the letter but the chief and myself. We watched Trelawney ourselves. We were after Waldstein then. He was always slippery, and at that time we reckoned he was vanishing an average of one girl a week through the Pan-European Concert Agency, which was one of his most profitable incarnations. But he was clever, and he never appeared in person, and there was never a line of evidence. Then I had the inspiration. I suggested to the chief that he go to Trelawney with the story that one of Waldstein's men had squealed. He saw the point, and agreed. He told the tale of Trelawney, as he'd naturally have told him anything else in the way of business that he was pleased about. Waldstein was in Paris, and the chief said that the Sûreté had arranged to intercept any letters, telegrams, or telephone calls addressed to him, so that no one could warn him, and one of our men was going over to arrest him the next morning. And the next morning, bright and early, Trelawney chartered a special aëroplane and set off for Paris."
"No!"
"He did. The chief and I, having been waiting for just that, chased him in a faster aëroplane, and trailed him all the way from Le Bourget to Waldstein's hotel. Then, when we'd heard him ask for Waldstein at the office, the chief tapped him on the shoulder."
"And?"
"He'd got his story pat. Gosh, I've never met such a nerve! He just blinked a bit when he first saw the chief and me, but from then on he never batted an eyelid. We went into a private room, and the chief told him the game was up.
" 'What game?' asked Trelawney.
" 'What are you doing here?' asked the chief.
" 'What you told me to do,' says Trelawney.
" 'I never told you to come here,' says the chief.
"The chief says Trelawney went a bit white then, but I never noticed it. Anyway, Trelawney's story was that he'd been called up by the chief early that morning and told to go over and attend to Waldstein himself, as there was some difficulty with the French police, and Waldstein was likely to get away during the argument. We asked him why he hadn't gone to the Quai d'Orsay first, to present his papers, and he said the chief had told him to get Waldstein first and argue afterwards."
"Well?"
Cullis shrugged.
"After that, it was all over."
"Don't see it," said the Saint. "If Trelawney was guilty, why should he tell that story to the very man who would know at once that it wasn't true?"