How to Write a Scientific Secret Code

Sherlock Holmes deciphers a secret code. Image: Mountain Xpress

Dear Reader, we always try to look out for your best interests.

So, today! We have a life-saving tip should you ever find yourself with a Top Secret Invention that could change the Course Of History.

We learned this valuable information from the WWII-era film Sherlock Holmes and the Secret Weapon (1942). This mystery/thriller/propaganda flick stars the fab Basil Rathbone and Nigel Bruce as the crime-solving Sherlock Holmes and Dr. John Watson.

In this somewhat bizarre movie, Holmes infiltrates a Nazi spy ring that plans to kidnap noted scientist, Dr. Tobel (pronounced To-BELL, played by William Post Jr). Tobel has invented a deadly accurate, state-of-the-art bomb sight, which he’s loaning to the British War Effort. Naturally, the Nazis want to nab this Invention before the Allies put it to use.

But they’ll have to get around Sherlock Holmes first, and Holmes is, among other things, a Master Of Disguise. He wears three Nazi-fooling disguises in this film: 1) to escort Dr. Tobel to London; 2) to get valuable info when Tobel vanishes; and 3) to rescue Tobel from the nefarious Professor Moriarty (Lionel Atwill).

But Holmes’ theatrical apparel pales in comparison to his Powers Of Deduction, which he needs to solve the mysterious code Dr. Tobel leaves behind when he unexpectedly disappears.

Tobel’s code is composed of dancing stick men, and these figures reveal a surprise. The bomb sight has been disassembled into four pieces, each of which has been entrusted to a British Scientist.

“What a fascinating plan!” says Holmes, because he admires a fascinating Plan.

Tobel’s mysterious code. Image:

At first glance, Tobel’s code looks like a crude set of hieroglyphics, as though it’s depicting a strange pantomime or mob dance. But Holmes quickly realizes each figure represents a letter of the alphabet.

This is known as a Monoalphabetic (Letter) Substitution which means, according to, “each letter of the alphabet is replaced according to the key with another letter or symbol.”

It’s easy to figure out the key. In the English language, the most common letter is E, followed by T, A, O, I, N. (You can verify letter frequency here.)

All Holmes has to do is determine which figure occurs most frequently; he can assume this is the letter E. Then he can deduce the letter T, and so on.

See? Being a secret agent may not be as difficult as we’ve been led to believe.

However, because this code is simple to write, it’s also easy to decipher. Take note, Dear Reader – you may have to do what Dr. Tobel has done, and reverse the order of the letters so you and your Top Secret Invention aren’t discovered too soon.

Can you spot Sherlock Holmes in disguise? Image: alamy

We’d like to say this film is based on the Sherlock Holmes short story, The Adventure of the Dancing Men, by Arthur Conan Doyle, but we can’t. It looks like the only thing filmmakers have taken from the story is the stick figure code, which they transplanted into World War II.

One of the main problems with this film is Dr. Tobel: He’s surprisingly dull-witted for a renowned scientist. He’s smart enough to invent things and write fancy codes, but he can’t outwit Professor Moriarty, who kidnaps him so he can bargain with the Nazis.

Alas, this is what happens when you do groundbreaking work without a peer group.

If Tobel were accountable to some kind of Team Leader or Department Head, then all this nerve-wracking business could have been avoided. Sherlock Holmes is a smart man, but it’s unfair to make him solely responsible for Tobel and, by extension, the Fate Of The Free World.

We can’t enthusiastically recommend Sherlock Holmes and the Secret Weapon, because there are too many plot holes. However, if you’re a Sherlock Holmes fan, you ought to see this film – if only for tips on writing and deciphering a secret code.

Sherlock Holmes and the Secret Weapon: starring Basil Rathbone, Nigel Bruce, Lionel Atwill. Directed by Roy William Neill. Written by Edward T. Lowe, Scott Darling & Edmund L. Hartmann. Universal Pictures, 1942, B&W, 68 mins.

This is part of the MOVIE SCIENTIST Blogathon hosted by Christina Wehner and yours truly.



  1. Invaluable information! Especially about the dangers of the absence of a peer group. Definitely, your post needs to be handed out to all movie scientists. They would be so much better off.

    I’m actually a fan of Basil Rathbone, Nigel Bruce, and Lionel Atwill – and I don’t ever want to turn into a lonely scientist – so I will have to give this film a viewing. Thanks!

    Liked by 1 person

  2. I thought this was a nice, fun little adventure. It’s been too long since I watched it to remember the plot holes, but I probably didn’t care about them too much because it’s mostly just about getting to see Holmes and Watson, fighting Nazis no less. Great as they are, the definitive Holmes for me will always be Jeremy Brett. If you ever get a hankering to see a version of The Dancing Men that follows Doyle, check out Brett’s; it’s the bomb.

    Liked by 1 person

    • Thanks! I have a lot of catching up to do with this Sherlock Holmes series from Universal Studios, but I don’t want to go through them too quickly, because after a person has seen them all, there are no “new” ones left.


  3. Nice analysis. I remember seeing this film a while back and being a little annoyed that the phenomena of Sherlock Holmes (which was so ground-breaking for the 19th century in which Conan Doyle was writing) was transplanted into WWII (where the idea of using logic and clues to solve a crime was the rule rather than the exception). But I do love Basil Rathbone as Holmes.

    The Dream Book Blog

    Liked by 1 person

  4. I’m a total Sherlock Holmes fangirl, but I haven’t watched any of Basil Rathbone’s films except for The Adventures of Sherlock Holmes with Ida Lupino — and I can’t even remember it that well! I suspect my avoidance is because I’m such a fan that I hate seeing how some adaptations mess up the stories. Not to mention the fact that everyone has to use Irene Adler and/or Professor Moriarty, as if they were the only people Holmes associated with. (Okay, climbing off my soap box now…)

    It does sound intriguing that Universal transported Holmes and Watson to WWII, and I really do enjoy the thought of Rathbone as the detective, so perhaps I’ll keep a more open mind for this film series!

    Liked by 1 person

    • Michaela, you are welcome on the soap box any time! As for Sherlock Holmes adaptations, I’m not enough of an expert to rate any of them, except to say I enjoy the original written stories best.

      Basil Rathbone is a terrific Holmes, and this movie has plenty of entertainment value. If you did see it, I’d be curious to know what you thought of it.


  5. I got this movie as part of a package deal several years ago. A company called DVDTee put out a bunch of low-budget public domain movies with a tee-shirt that had the movie poster on it. I picked a lot of them up at a local bookstore for $7 each. I figured hey, even if the movie sucks I get a nice tshirt for $7. This was one of the better offerings. Of course with Sherlock Holmes you can’t go TOO wrong. Good review.

    Liked by 1 person

    • You can’t go wrong with a $7 T-shirt. And you’re right about any Sherlock Holmes adaptation – you have to work really hard to screw it up. This film is plenty entertaining, no? It’s fun to see the Master of Disguise at work here.


  6. I’m pretty sute I’ve read the story this film is based on, but I haven’t seen the movie. But I find it curious that even Sherlock Holmes was used in a propaganda film to boost the moral and fight Nazis. Conan Doyle must have been amused.
    Thanks for co-hosting this event!

    Liked by 1 person

  7. Great review. I laughed out loud several times and Bruce and Rathbone are always a treat to watch no matter how silly the plot. I also remember the code in the original Dancing Men story being pretty easy to decipher, but, of course, only Sherlock Holmes can figure it out.

    Liked by 1 person

  8. I find the entire Universal Studios Sherlock Holmes series to be quite entertaining, and I eat them up like candy! I feel I run across “Secret Weapon” quite often as there are channels (I think the one called “Movies” on cable tv) that show this public domain film frequently. What I like best about the Holmes Universal series is that most of the films are a little more than an hour long, and pack so much action and plot into it. The actors’ characterizations are wonderful, and they always capture my interest when they’re on tv. Thank you for writing such a clever post!

    Liked by 1 person

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