Since then I've read dozens of locked-roomers (or "impossible murders") and I have developed firm opinions about the genre. I have no truck whatsoever with the ones that have a supernatural solution or where the author doesn't give you enough information to solve the case for yourself.A locked-room problem lies at the heart of my new novel, In The Morning I'll Be Gone, in which an RUC detective has to find out whether a publican's daughter who fell off a table in a bar that was locked from the inside was in fact murdered. Firstly I had to assure the reader I was not cheating about the facts: the pub was indeed locked and bolted from the inside, there were no secret passages and certainly no supernatural element. Then, of course, I had to give the reader all the necessary information so that they could solve the case at the same time or before the detective. When it works you should be able to read a locked-room mystery twice, the second time spotting the clues and seeing how the whole thing fits together.When a locked-room mystery doesn't work the solution makes you groan and the book gets hurled across the room. In The Murders in the Rue Morgue an elderly Frenchwoman is killed in a locked room on the fourth floor. The solution – spoiler alert – is that the murder was done by a tame orang-utan who climbed in through the open window with a straight razor. Do that sort of thing nowadays and your book would rightly get chucked, probably back at your own head during a signing.The golden age of the locked-room mystery in Anglo-American detective fiction has largely passed, but in France Paul Halter has been churning out original impossible murder novels since the mid-1980s and in Japan the great Soji Shimada virtually invented the "logic problem" sub-genre which is still extremely popular.Mixing classic and contemporary with no supernatural activity allowed, these are my 10 favourite locked-room/impossible murder novels:10. The Moonstone by Wilkie Collins (1868)Rachel Verinder's cursed Indian diamond the Moonstone disappears from her room after her birthday party. This is only a rudimentary locked-roomer, but as the first and still one of the best detective novels it had to be on my list.9. The Case of the Constant Suicides John Dickson Carr (1941)Dr Gideon Fell investigates an alarming number of "suicides" at a remote Scottish castle. The deaths have taken place in completely inaccessible rooms. Dickson Carr was rightly known as the "master of the locked-room mystery" and this entire list could, with some justification, have been made solely from JDC books.8. And Then There Were None by Agatha Christie (1939)Eight people with guilty secrets are invited to an isolated island off the coast of Devon where they begin to be murdered one by one. When there are only two of them left the fun really begins. Previously published under two equally unfortunate titles.7. Suddenly At His Residence by Christianna Brand (1946)In another part of Devon Sir Richard March has been found poisoned in his lodge. A sand covered pathway leading to the lodge is rolled daily by the gardener. Only one set of footprints is found leading to the lodge and they belong to Claire, who discovered the body. A witty and engaging mystery from a writer who was another locked-room specialist.6. The Big Bow Mystery by Israel Zangwill (1892)Mrs Drabdump's lodger is discovered with his throat cut, no trace of a murder weapon and no way a murderer could have got in or out. Arguably the first proper locked-roomer and still a classic.5. The Mystery of the Yellow Room by Gaston Leroux (1908)Miss Stangerson is found severely injured, attacked in a locked room at the Chateau du Glandier. Leroux provides maps and floor plans showing that an assailant could not possibly have entered or escaped.4. The King Is Dead by Ellery Queen (1951)King Bendigo, a wealthy munitions magnate, has been threatened by his brother Judah, who announces that he will shoot King at midnight at his private island residence. King locks himself in a hermetically sealed office accompanied only by his wife, Karla. Judah is under Ellery Queen's constant observation. At midnight, Judah lifts an empty gun and pulls the trigger and at the same moment, in the sealed room, King falls back, wounded with a bullet. No gun is found anywhere in the sealed room and the bullet that wounds King came from Judah's gun – which didn't actually fire. Good, huh?3. La Septième hypothèse by Paul Halter (1991)Two men toss a coin and whoever loses has to commit a murder and try to pin the blame on the other. There are only two possible suspects to the subsequent crime and both have ironclad alibis. Seven solutions present themselves to the detectives in this ultra-twisty novel.2. The Tokyo Zodiac Murders by Soji Shimada (1981)A snowy evening in the Shōwa period of pre-war Japan. A wealthy artist, Heikichi Umezawa, is finishing up his great cycle of paintings on Zodiacal subjects when his head is smashed in with a blunt object. The studio is locked from the inside and the suspects have alibis. Over the next four decades many of Umezawa's family members are also gruesomely killed, most in "impossible" ways. In a series of postmodern asides Soji Shimada repeatedly taunts the reader explaining that all the clues are there for an astute observer.1. The Hollow Man by John Dickson Carr (1935)Someone breaks into Professor Grimaud's study, kills him and leaves, with the only door to the room locked from the inside, and with people present in the hall outside the room. The ground below the window is covered with unbroken snow. All the elements are balanced just right in this, the best of Dickson Carr's many locked-room problems.(theguardian.com)ANN.Az