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This Week on Mystery Theatre:
Knock-Code Charts & Ancient Alphabets

March 13th, 2023

Can the arrangement of carved squares on the front of a locked wardrobe provide a clue for decoding the tapping sounds coming from within? And what about the red-and-white dragon heads in the center of each square? Could they possibly indicate the language of the coded message?

Those are just some of the questions you and mystery writer August LaFleur will consider in this week’s installment of Prime Stage Mystery Theatre.

The episode drops on March 16, at which point I’ll include both a link here and a player at the bottom of this post.

If you’d like to listen to this week’s installment without any additional clues, you might want to bookmark this page and come back after listening to Act III.

However, if you’d like a preview and a few hints that might help solve the mystery, read on.

As you will recall, Act I of “The Ælf and the Wardrobe” opens with mysterious tapping sounds that lead you to a locked cabinet in a theatre basement. And since the solution to a mystery often lies in a careful examination of relevant details, we might take a good look at the design of the locked doors themselves.

The locked cabinet from “The Ælf and the Wardrobe.” Note the carved squares and red-and-white dragon heads. >>>

In addition, Act II introduces a form of encryption called tap or knock code, in which each letter of the English alphabet is assigned a numbered position on a code chart consisting of five rows and five columns (pictured below).

Thus, as we discovered in last week’s installment, “Each letter [is] assigned a pair of coordinates—one pertaining to its row, the other to its column,” and the numbers of those coordinates can then be communicated “through knocking or tapping sounds.”

Sounds easy enough, but then–at the end of last week’s episode–we realized that the code we are trying to decipher contains a set of six taps, evidently referring to a sixth column that does not exist on the English knock-code grid. So what gives?

For more information on the chart above and on the history of knock-codes, check out the blog post Cracking the Code.

When considering the need for a six-column grid, some listeners recalled a comment made by August LaFleur in last week’s episode. “Knock codes,” he said, “have been around for centuries, first developed in Ancient Greece. The Greek alphabet fits quite neatly into a grid of 24 rather than 25 squares.” And when considering the arrangement that might accommodate a 24-square gride, we might come up with the chart pictured here.>>>

But what about the red-and-white dragons? August LaFleur has speculated that they might be a reference to a medieval king written about in Geoffrey of Monmouth’s History of the Kings of England. We covered that king in a previous post, which you can find here, and if the dragons are in fact a reference to Monmouth’s 5th-century king, we might ask if the 24-letter Old English alphabet might yield the grid we need to decode the tapping sounds.

Give it a try. Click here to listen to the taps, then use the Old English chart of 24 squares (pictured left) to decode the message. Naturally, you’ll need to translate the results into 21st-Century English. But that shouldn’t be too tough in this age of on-demand information.

In any event, these images should provide a useful supplement to this week’s episode.

As always, if you have a question or comment about any of our mystery stories, you can reach us by posting at the bottom of this page or by dropping a note at

This Week on Mystery Theatre:
Cracking the Code

March 6th, 2023

The irregular tapping came from the other side of the sheet-metal wall that separated Paul’s and Harold’s cell from the totally enclosed tank for desperados next door.

Experimentally, Paul tapped on his side.

“Twenty-three—eight-fifteen,” came the reply. Paul recognized the schoolboy’s code: one for A, two for B … twenty-three—eight-fifteen” was “Who?”

That’s a rudimentary version of tap code (also known as knock code) depicted in Kurt Vonnegut’s Player Piano, a novel that a recent report on NPR called prescient in its anticipation of “the current state of AI and automation.” You’ll find it on page 306 of the Dial Press Trade Paperback edition, and it’s just one of a number of literary accounts of a code system introduced in this week’s installment of Prime Stage Mystery Theatre.

A more sophisticated version of the code system is depicted in Arthur Koestler’s Darkness at Noon,  a novel that The Modern Library ranked in the top ten of the 100 best English-language novels of the 20th century. The passage below is from page 24 of Scribner’s hardcover edition. Like the scene in Vonnegut’s book, it takes place in a prison cell. The image below is from a 1955 NBC production starring Claude Rains, which aired on Producers Showcase in 1955.

The wall was thick, with poor resonance; he had to put his head close to it to hear clearly and at the same time he had to watch the spy hole. No. 402 had obviously had a lot of practice; he tapped distinctly and unhurriedly, probably with some hard object such as a pencil. While Rubashov was memorizing the numbers, he tried, being out of practice, to visualize the square of letters with the 25 compartments—five horizontal rows with five letters in each. 

The novels were first published in 1952 and 1941 respectively, but knock codes have been around for centuries, first developed in Ancient Greece and often used by prisoners (as noted in the above passages).

In English, the tap-code grid consists of 25 squares arranged evenly into five stacked rows, in which all but one of the squares contains a single letter, starting with A in the upper left and continuing through to Z in the lower right. The one exception, the middle square of the top row, contains both C and K, thus enabling the grid of 25 squares to accommodate the entire 26 letters of our Latin-based alphabet. This is the same grid described in Koestler’s book, as well as in the novel The Ash in Ælf Mystery that August LaFleur sites in this week’s installment of Mystery Theatre.

The graphic above is from

Tap codes and the better-known dot-dash system Morse Code (click here for a chart) were among the topics that folks discussed at last weekend’s Mystery Theatre display in the lobby of The New Hazlett Theatre, where theatergoers attending the opening of The Lion, The Witch, and the Wardrobe gathered to examine some of the clues presented in this month’s mystery.

Theatergoers and mystery fans attempt to crack the code at the Mystery Theatre Display in the New Hazlett Theatre.>>> 

But will either Morse or knock code decipher the sounds from Act I of “The Ælf in the Wardrobe”? Is it possible that some other tap code variation is being employed? Or could it be that the sounds aren’t codes at all?

Those are some of the questions we’ll be pondering this week. So keep your code charts handy, and get ready for some surprises when Mystery Theatre returns this Thursday with the second installment of “The Ælf in the Wardrobe.”

I’ll meet you there!