Carr was the acknowledged master of the impossible crime story, and "The Three Coffins" may be his best. He begins his book with a direct challenge to the reader, laying out the situation he intends to present: in one case, the murderer was seen to enter the room with his victim, but when witnesses broke down the door, they found the victim dying and the murderer had vanished from the room; in the second case, the victim was shot at close range in the middle of the street, with watchers at either end, but nobody saw the murderer and no footprints appeared in the snow. It is brilliant.

John Dickson Carr again, writing under the name Carter Dickson, produces a nightmare situation: the central character is summoned to meet with his future father-in-law. While the two men are talking in a locked room, the younger man realizes he has been drugged. When he awakens, some 20 minutes later, he finds his father-in-law dead, stabbed with an arrow that had been hanging on the wall. The doors and windows are securely locked and bolted on the inside. Nobody else is in the room. And somebody is pounding on the door demanding that he open it. The solution, as we are told repeatedly by Dickson's detective, Sir Henry Merrivale, involves the use of a Judas window. What, you may ask, is that? Something that nearly every room has, says Sir Henry, but almost nobody ever notices This is widely considered one of the finest locked room mysteries ever written.

This may be the best book Christie ever wrote, although it features none of her popular detective characters. Ten people find themselves stranded on an island — and all apparently are marked for death. As they are murdered, one by one, you must figure out how the murders are happening and who could be responsible for them. Christie provides fair clues — not many, but enough — that could lead you to the answer to this seemingly impossible problem. But probably not.

This will be hard to find — it's a novella, not a full-length novel, so you'll have to look for collections of Queen short stories to locate it. But what a story: Ellery Queen (the detective character and author have the same name) is called to a remote house on New York's Long Island to solve a mystery. The house has a companion house directly across a driveway. But when Ellery wakes up on his second day there, he finds the companion house has disappeared completely. There is nothing but an unbroken field of snow where the house — which Ellery had toured the previous night — had been. Oh yes, there's a rational solution — and you're given the clues to it.

This is another short story, starring Futrelle's character, "The Thinking Machine", but it has been widely anthologized and should be easily available. It's not, technically speaking, a crime story. Instead, Professor S. F. X. Van Dusen, "The Thinking Machine", makes a wager that he can escape from the condemned cell in a prison within one week, using nothing but the everyday clothes he is allowed to wear into the cell, and despite being heavily guarded by the prison staff. Impossible? See how it's done!

This may be the best of Sayers' novels featuring Lord Peter Wimsey. The body of an unknown man is discovered in a graveyard. There is no indication of how the man died, although he has a look of absolute horror on his face. The secret of who the man is will be revealed before the overwhelming mystery of how he was killed. It is a powerful, well-written drama.

A particularly nasty crime: the victim is crushed by a massive tombstone. But how could it possibly have happened? Crispin's Oxford-don-turned-detective, Gervase Fen must solve the puzzle in the midst of a chilling romp that involves British academics and clerics, witchcraft, and a thoroughly unpleasant nest of spies. The tone ranges from wild humor to pure horror.

First published in 1907, it is considered an early classic of the genre and was much admired by authors such as John Dickson Carr. A woman screams inside a locked room. When the door is broken down, she is discovered, badly wounded and bleeding, but there is nobody else in the room. How could anyone have escaped? This is the central mystery — but it will not be the only one.

Vacationing on Catalina Island, schoolteacher Hildegarde Withers (whom Palmer used to refer to as a "meddlesome old battleaxe") is confronted by an impossible murder: a man is poisoned in mid-air on a plane, in full view of the other passengers and crew, but nobody appears to have gone near enough to the victim to poison him.

This was the first of an entire series of mysteries by mountaineer Showell Styles using the name Glyn Carr, featuring the exploits of Abercrombie "Filthy" Lewker, who manages to solve crimes that take place in a "large open-air locked room," which aptly describes the sport of mountain climbing. In this case, a rather disagreeable young man is murdered while climbing a mountain — and while roped to another climber — yet there seems to be no way the murderer could have approached and killed the victim unseen.