In its august history, the mystery novel has undergone great development in the hands of its practitioners. Any new development that other writers go on to imitate is called a "convention" (or con, for short).

One of the oldest of these conventions is the Locked Room Puzzle, dating back to Saint Edgar Allan Poe and never going out of style. The Locked Room convention is not an easy thing to do well, although it is done frequently. The following guidelines might be of help to those attempting this particular convention for the first time.

All Dressed Up and No Way to Go

1. Only cozy writers may use this convention. What could be cozier than a locked room?

2. All points of egress/ingress to the scene of the murder are, well, locked.

3. The cost of the convention is usually no greater than $140, but that does not include hotel charges.

4. The hallmark of the Locked Room Convention is the smashed timepiece. In the room, it is mandatory for the police to find and impound a timepiece that was smashed, thus stopping the hands of the timepiece at precisely the moment of the murder.

   This can mean one of three things:

   • The smashed clock is a good clue

   • The smashed clock is a red herring, cleverly conceived by the killer

   • It was not a Timex

5. The Sisters in Crime Breakfast will be scheduled too early in the morning for everyone but those drunken authors who never went to bed the night before and are lined up at the door of the Presidential Ballroom, looking for Bloody Mary relief and a place to check their lampshades.

6. The points of egress/ingress in the locked room must total at least 15, including windows, doors, chimneys, secret passageways behind revolving bookcases, trap doors, dumb waiters, and mouse holes. This is to keep the detective busy and the reader on his toes (on his own toes, that is, not on the detective's toes.)

7. The whole point of the Locked Room Convention is hidden behind one larger, more apparent, assumption:
   • The Assumption: it was impossible for the murder to have occurred.

   • The Real Purpose: The murderer has been busy not only committing a grisly crime but also — the selfish bastard — establishing an alibi for him/herself.

8. The alibis for the minimum of 6 suspects can include but are not limited to:
   • running down to London for an unexpected appointment with one's solicitor

   • drunkeness

   • occupying a love nest

   • cooking the meal (proven by the condition of the meal, which is still warm on the table)

   • it's too early to commit a murder, much less get out of bed for a Sisters in Crime Breakfast

   • being too old, too frail, or too female to wield the murder weapon (which will be discussed below)

   • blindness

   • advanced pregnancy

   • having one's caddy swear that one was on the links at the time of the murder (remember the smashed timepiece) — and, the potential suspect shot three under par

   • chopping wood, which does not look quite right to the police because it's as hot as blazes during a record heat wave and a cord of wood is already stacked neatly beside the manor house — the reader may be sure that the suspect having this alibi is not the murderer

9. The weapon must be in the locked room, and it is essential that the weapon be monstrously heavy (see the "too old, too frail, too female" alibi, above).

   The weapon is usually an emerald-studded scimitar covered with lurid inscriptions in Latin, which only readers who are also classical scholars will be able to decipher as being absolutely filthy jokes perpetrated by the author for her own amusement. We can't do it all for the reader's sake. Scribo ergo sum.

10. Lawrence Block will interview himself on the most heavily attended panel.

11. The awards given out annually for the best locked room murders are called the "Beatles," because, since every author wants one, the master of ceremonies must often repeat "GET BACK!"

12. If the author has done the job properly, even when the solution of the crime is revealed (usually at a gathering of all the suspects, at which tea is served by a nervous maid who drops things), we simply don't believe it and come away from the experience with the feeling of having had our legs pulled.

Know the feeling?

Submitted by Polly Whitney, who wants a Beatle.