8vo. Portrait frontispiece. Original pictorial yellow-orange cloth stamped in black after a design by Pierre Leffite; DUST JACKET (extremities a bit faded, light chipping to spine ends and fore-corners, tiny cellotape repair near foot verso); slipcase and folding chemise. Provenance: Otto Penzler, American editor of mystery fiction and proprietor of The Mysterious Bookshop (his sale, Heritage, 15-16 October 2020, lot 45272).

THE OTTO PENZLER COPY OF THE FIRST EDITION IN ENGLISH OF THE FIRST "LOCKED ROOM MYSTERY". First serialized in L’Illustration in 1907 before appearing in book form in Paris the following year, the novel quickly became one of the foundational works of modern detective fiction. Its central puzzle—the attempted murder of Mlle. Stangerson inside a chamber locked from the inside—was widely regarded as one of the most ingenious “locked-room” problems ever devised. IN THE EXCEEDINGLY RARE DUST JACKET: According to online records, there have been only two copies appearing at auction in dust jacket in at least a century (this copy, and another that was mostly restored). A Haycraft Queen Cornerstone.