Here's a snapshot of what I think is published for the first time in September 2023 (and is usually a UK date but occasionally will be a US or Australian date). 69 titles this month. September and future months (and sometimes years) can be found on the Future Releases page. If I've missed anything or got the date wrong, do please leave a comment.
Please note that, unless specifically mentioned, when a book has differing print and ebook release date, I use the print release date. Translators' names are included where known.
• Amphlett, Rachel - Cover the Bones #5 Detective Mark Turpin• Archer, Jeffrey - Traitors Gate #6 Detective Chief Inspector William Warwick
• Beaton, M C - Agatha Raisin: Dead on Target (with R W Green) #34 Agatha Raisin, Retired PR person, Cotswolds
• Beevis, Keri - The Boat House
• Benn, James R - Proud Sorrows #18 Billy Boyle, WW2
• Briggs, J C - The Waxwork Man #11 Charles Dickens and Superintendent Jones
• Bright, Verity - Murder by Invitation #15 Lady Eleanor Swift, 1920s
• Burnside, Heather - Redemption #3 Manchester Thrillers
• Burrowes, Grace - A Gentleman of Dubious Reputation #2 The Lord Julian Mysteries
• Cambridge, Colleen - Murder by Invitation Only #3 Phyllida Bright, housekeeper to Agatha Christie
• Carson, John - Now or Never (ebook only) #19 DCI Harry McNeil
• Cartwright, Jack - Her Dying Mind (ebook only) #11 Wild Fens Murder Mystery
• Clark, Anne Wyn - The Secrets of Mill House
• Clarke, Sarah - The Ski Trip
• Comley, M A - Sinner #10 DI Sally Parker
• Cookman, Lesley - Murder in Autumn #24 Libby Sarjeant, middle aged actress/investigator, Kent
• Cox, Helen - A Body in the Borderlands #8 Kitt Hartley, Yorkshire
• Croft, Kathryn - The Wedding Guest
• Day, Becca - The Secrets We Buried
• Ellis, Emmy - Revived #21 Cardigan Estate
• Ellis, J R - The Brewery Murders #9 Detective Chief Inspector Oldroyd, Yorkshire
• Everett, F L - Murder in the Blitz #1 Edie York, 1940s
• Francis, Dick - No Reserve (by Felix Francis)
• Galbraith, Robert - The Running Grave #7 Cormoran Strike
• Gatland, Jack - Kissing A Killer #16 DI Declan Walsh
• Gillan, Florence - The Forfeit
• Glass, Ava - The Traitor #2 Alias Emma series
• Golding, Melanie - The Sight
• Hanley, C B - Blessed are the Dead #8 Edwin Weaver, C13
• Herron, Mick - The Secret Hours
• Hood, D K - Dark Angel #1 Detective Beth Katz
• Hood, D K - Shadow Angel #2 Detective Beth Katz
• Howell, Lis - The Gardener in the Graveyard #5 The Norbridge Chronicles
• Hunter, Cari - A Calculated Risk
• Hunter, E V - A Marriage To Murder For #3 Hopgood Hall Murder Mysteries
• James, Peter - Stop Them Dead #19 Detective Superintendent Roy Grace, Brighton
• Johnstone, Doug - The Opposite of Lonely #5 Skelfs family
• Kinsey, T E - A Fire at the Exhibition #10 Lady Emily Hardcastle, 1908
• Kovach, Carla - Her Hidden Shadow #14 Detective Gina Harte
• Lee, M J - The Irish Convict (ebook only) #10 Jayne Sinclair Genealogical Mysteries
• Lindsay, Douglas - I am Multitudes #11 DS Hutton
• McCabe, Amanda - Flora Flowerdew and the Mystery of the Purloined Papers #2 Flora Flowerdew, Victorian Era
• McLean, Rachel - The Ghost Village Murders #9 DCI Lesley Clarke, Dorset
• McLean, Rachel & Hames, Joel - The Harbour #1 Cumbria Crime
• MacLean, S G - The Winter List #6 Damian Seeker, agent of the Lord Protector, 1654
• Mackay, N J - The Quiet Dead #1 DI Sebastian Locke
• Malliet, G M - The Washing Away of Wrongs #8 Max Tudor, Vicar
• Malone, Michael J - The Murmurs #1 Annie Jackson
• Matthews, L V - Silent Waters
• Nickson, Chris - Rusted Souls #11 Detective Inspector Tom Harper, Leeds Police, 1890s
• Organ, Emily - Death in Westminster (ebook only) #5 Augusta Peel, 1920s
• Osman, Richard - The Last Devil To Die #4 The Thursday Murder Club
• Penrose, Andrea - Murder at the Merton Library #7 Wrexford & Sloane
• Peston, Robert - The Crash
• Phifer, Helen - Stolen Darlings #10 Detective Morgan Brookes
• Ripley, Mike - Mr Campion's Memory #11 Albert Campion
• Ross, L J - The Bay #3 Summer Suspense Mysteries
• Schellman, Katharine - Murder at Midnight #4 Lily Adler, London, 1815
• Seddon, Holly - The Short Straw
• Smith, Alexander McCall - From a Far and Lovely Country #24 Mma Ramotswe, PI, Botswana
• Swann, Leonie - The Sunset Years of Agnes Sharp tr. Amy Bojang #1 Agnes Sharp
• Thomson, Lesley - The Mystery of Yew Tree House #9 Stella Darnell
• Tobin, Sam - Wind Up Dead #3 Manchester Underworld
• Veste, Luca - Trust In Me
• Wallace, Joanna - You'd Look Better as a Ghost
• Ward, Cameron - The Safe House
• Waugh, Daisy - Old School Ties #3 Tode family
• Wells, Kate - Murder on the Farm #1 Jude Gray
• Young, Glenda - Foul Play at the Seaview Hotel #3 Helen Dexter, Scarborough