Mr. Hardy whistled solemnly.

“Good work.” He turned the wig over and over in his hands, carefully examined it under a microscope, and then tossed it back on the desk.

“There aren’t so many wigs sold that one can’t trace them,” he observed. “This happens to be made by a small company that doesn’t turn out a great many wigs in a year. It’s a sort of side line with them.”

“How can you tell?”

“There’s a little mark on the inside that distinguishes the manufacturer. Just a trademark⁠—hardly noticeable.”

“And we found these as well,” said Frank, handing over the coat and hat.

Mr. Hardy’s eyes opened wide.