EQMM’s July/August issue, on sale now, is dedicated to the traditional mystery. Leading it off, with “The Locked Room Library,”  is Gigi Pandian, the author of ten traditional mystery novels (the Jaya Jones Treasure Hunt mysteries and Accidental Alchemist mysteries) and more than a dozen impossible-crime short stories. Her short fiction has won Agatha and Derringer awards, and if you enjoy “The Locked Room Library” (as we’re sure you will!) and want to visit that setting again, it’s featured in Gigi’s forthcoming locked-room mystery novel, Under Lock and Skeleton Key (St. Martin’s Minotaur/March 2022). Meanwhile, here are some helpful clarifications, from an expert, of what an impossible-crime story, a closed-circle mystery, and a locked-room mystery are. —Janet Hutchings

I’m thrilled to see traditional puzzle plot mysteries regaining popularity in recent years. They’ve always been my favorite type of mystery, because in addition to whatever other wonderful literary elements are present in a book or short story, the reader knows they also have a deviously clued mystery to solve.

With so many new readers warming to the genre, I’ve noticed a bit of confusion regarding terms used to discuss these mysteries. Most mystery readers have heard the term locked room mystery, but what exactly does it mean?

Closed circle mystery. A small number of people are isolated when a crime occurs in their midst. There’s no way for them to leave or be rescued, so there’s an oppressive feeling because the characters know that someone in their midst is a killer.

An example is an island with no boats or a country house during a snowstorm. An image of many Agatha Christie novels no doubt comes to mind. This plot set-up is often conflated with being a locked room mystery. It’s true many mysteries feature both a closed circle and a locked room puzzle, but the two aren’t the same thing. So what is a locked room mystery then?

Locked room mystery. A crime has been committed in a room or other impenetrable location where it appears impossible for the crime to have been committed. The key is that the situation appears truly impossible, not simply that a small group of characters are cut off from the world.

An example is a dead man found inside a windowless room that’s been sealed from the inside, dead from a gunshot wound that people outside the room heard fired, yet inside the room there’s no gun and no way for the culprit to have escaped; there’s no rational way for the crime to have been committed, so the character might wonder if it was the family ghost seen roaming the mansion’s hallways. Ellery Queen and John Dickson Carr are two authors who excelled at coming up with ingenious solutions to these seemingly impossible puzzles.

Impossible crime. The umbrella term under which locked room mysteries fall. It covers any seemingly impossible situation, such as a priceless jewel vanishing in front of everyone’s eyes. In practice, an impossible crime mystery serves as a synonym for a locked room mystery. It’s a more accurate description of what readers think of as a locked room mystery, though the term never caught on as widely.

Miracle problem. The term for impossible crime stories preferred by mystery fiction historian Douglas G. Greene. The idea of a miracle problem captures the spirit of why impossible crimes are so tantalizing—because it appears the crime could only have been committed through a miracle, because there’s no logical, earthly way for it to have occurred.

No matter what you call it, these are the elements included

Fair play detective story. Readers should have all the clues they need to solve the crime—all the pieces of the puzzle—given the same information as the detective. Authors like Ellery Queen took this to an extreme, pausing from the narrative to directly address the reader, challenging us to solve the crime before the detective. After all, we’ve already been given all the clues we need.

Supernatural explanations are not allowed. Even though it appears that nobody could have committed the crime, the solution has to be logically viable. No miracles allowed.  

No secret passageways. Yes, secret passageways are wonderful in literature! I love them so much they’re a central element in my new Secret Staircase mystery series. But they have no place as the solution to a true locked room mystery. Their presence means a room wasn’t truly sealed, so the same logical puzzle isn’t there to be solved.

Also frequently included, but not required:

Stage magicians. Because of the seemingly impossible nature of the illusions created by stage magicians through misdirection, magicians are often used as detectives in locked room mystery stories. Their skills at creating seemingly impossible tricks are called upon by the police to use their skills in the opposite direction, seeing through what’s essentially a trick created by a criminal to deceive, rather than illusion thought up by a performer to entertain.

During the Golden Age of detective fiction, Clayton Rawson created one of my favorite sleuths, stage magician The Great Merlini. In the present day, Andrew Mayne’s character Jessica Blackwood is a former magician who brilliantly sees through impossible situations. I created Sanjay Rai, who performs magic as The Hindi Houdini, as a side character in my debut novel. I quickly realized he was the perfect character to solve seemingly impossible crimes, so he accidentally became the character featured in the vast majority of my locked room mystery stories.

Gothic atmosphere. In style, many locked room mysteries are similar to Gothic novels, because with no logical explanation, a supernatural explanation appears to be the only possible solution. Supposed hauntings are common, with ghost stories abounding. A ghost, after all, can be a helpful cover for a living murderer. John Dickson Carr excelled at creating misdirection through a ghostly atmosphere.

Whatever terms you use to describe these mysteries, I hope you’re having a marvelous time reading them.