Of significant note is the upcoming auction on the 4th March 2020 at Heritage Auctions, USA. Lot 45122 is Agatha Christie's The Mysterious Affair at Styles, A Detective Story, published in New York by John Lane Company in 1920. This is the true first edition of Christie's first novel. The novel was first published in book form in the United States in September, 1920. While there are some records that implied an October print date, there are also references in later printings to a September date. Surprisingly, it was not published in England until January of the following year. The Canadian edition was printed 2nd (October 1920), making the English edition the 3rd printing.
In addition to being Christie's first book, The Mysterious Affair at Styles is also noteworthy this is the 100 year anniversary of the book. For many years collectors paid significantly more for the later 1921 UK first edition, though in recent years the pricing disparity has narrowed as investors generally clamour for the true first printings. In addition, it is unlikely that there was much of a print run different between the UK and US versions - if any version had a smaller run it was likely the Canadian copy.
Affiliation: This book has a bookplate on the front pastedown for "Adrian Homer Goldstone", the noted bibliophile and author of bibliographies of John Steinbeck and Arthur Machen. It will be interesting to see the price realized on this current item as Heritage Auctions sold another copy of this book in their September 2019 auction - that one was from the Otto Penzler collectio and realized $10,625 US. With both having affiliations of arguably equal value and the conditions are very similar, it is possible that this one will sell for less solely because it is buried deep in an auction of mostly non-fiction items, and with only one other Christie book for sale - a somewhat common 1929 UK first of the paired short stories of Christie's "The Under Dog" and Oppenheim's "Blackmans Wood".
Condition: Small octavo. 296 pages. Original cream cloth boards with green titles and decorations to spine and front board. Boards lightly smudged. Very minimal wear to edges, with a couple of tiny dots of discoloration to top edge of pages. In fine condition, tight and square. Housed in a custom cloth-covered clamshell box.
Auction Terms: Online bidding open now. Auction will have live bidding too. Buyer's premium is 25% and included in quoted price. Currently the online bidding has the book at $2,600 US plus b/p, but I expect pricing to be near $10,000 all-in when all is done.