Fantastic pairing of two items: a choice ink signature, "Yours truly, Arthur Conan Doyle, May 3/10," on an off-white 5 x 3 card, encapsulated and graded by PSA/DNA as "MINT 9"; and a first edition, first issue of his classic Sherlock Holmes book The Hound of the Baskervilles, hardcover, 5 x 7.5, 359 pages, published in 1902 by George Newnes of London. Bound in the publisher's red pictorial cloth gilt, with points of issue including 'you' for 'your' on page 13, line 3. All 16 illustration plates by Sidney Paget are present. Autographic condition: very fine. Book condition: VG/None, with minor rubbing to boards, scattered foxing to textblock, and a small ownership inscription to first free end page.