From his note-case Robin now drew a folded square of paper identical in colour with the letter spread out before them.
“I found this on the carpet beside Parrish’s body,” he said. “Look, it’s exactly the same paper ...”
Behind the tortoise-shell spectacles the big man’s eyes narrowed down to pin-points as he caught sight of the sheet which Robin unfolded and its series of slits.
“Aha!” he cried—and his voice rang out clear through the room—“the grill, eh? Well, well, to think of that!”
He took the slotted sheet of paper from Robin’s hands and laid it over the letter so that it exactly covered it, edge to edge and corner to corner. In this way the greater part of the typewriting in the letter was covered over, and only the words appearing in the slots could be read. And thus it was that Robin Greve, Herr Schulz, and Dr. Collingwood, leaning shoulder to shoulder, read the message that came to Hartley Parrish in the library at Harkings....
ELIAS VAN DER SPYCK & CO.
GENERAL IMPORTERS
ROTTERDAM Rotterdam 25th Nov.
Codes
A.B.C.
Liebler’s
Personal