I will not be tagging this puzzle, purely because I don't want to give away exactly what is in it, but I will give you an "abstract" for it. (except for the one "computer-science" tag because I need that to post)

Abstract: This is not a single puzzle, I will give you two things to begin. One is a link, another is encoded English. The link goes to a Sherlock Holmes Collection PDF. The code, well, I'm not going to tell you what it is; but it does decode directly to English, and is not scrambled, or ciphered, there is direct correlation. The only thing about it that may make it difficult to decode is it's shortness, and therefore lack of data.
The code will help you find something in the PDF, that will take you to the next step. I cannot tell you what you will find in the PDF, but if you have a good guess then CTRL+F will shortcut you past having to solve the code. Solving the code will make it easier to find what you are looking for in the PDF. Though if you solve the code, then already having read a particular story in the PDF will help you know exactly where in the story to find the redirection to the next step of this "Puzzle Course". At worst, you'd have a tiny bit of Sherlock reading to do, but this is "Puzzling" on StackExchange, who here would complain about reading Sherlock?
The next step will require you to know a fairly intermediate-to-advanced knowledge of computers, because it will give you a link to a locked PDF and using your knowledge of computers will get you another code, which, once decoded, is the password for the PDF. Again, that code is just like the one I am giving here, it DIRECTLY correlates to English, is not scrambled, or anything mean like that. It's as direct as 1 = a 2 = b 3 = c. The PDF's password is like 20 characters long or something so don't bother trying to brute force it. The only reward for solving all this is the same as any other riddle, the congratulations of exceeding my intelligence hahaha

TLDR: Use the code to help you find a thing in the PDF, which will take you to another hidden code and another locked PDF, the hidden code helps you unlock the PDF, and once you do that you win. All codes directly translate to English, and no excessive amount of reading should be necessary with either PDF.

So... Here it begins.

First Code: 10=1==01110010=0==0=0111=01011=10

Sherlock PDF: Here.

Final notes: I have a document keeping track of the entire development of this course. If you think something does not work, let me know, and I'll fix it. Please leave an explanation if you downvote this, I'm alright with taking downvote hits but I really do appreciate feedback.


1 of 2 --- On the 0,1,=, code. All three of those symbols are arbitrary, you could replace them with 1,2,3, - a,b,c, - a,1,+, whatever you like. :)

2 of 2 --- On the 0,1,=, code. 10= is equivalent to English "t".

You may begin.

Note that I want people to solve this... so please help me help you get through it. I will give a good hint on how to break the first code in a day or two.

  • $\begingroup$ I think you need to lessen the text in the abstract bit, it is quite a read and may put people off $\endgroup$ Commented Nov 26, 2016 at 15:33
  • $\begingroup$ How's the TLDR? $\endgroup$
    – larkwiot
    Commented Nov 26, 2016 at 15:44
  • $\begingroup$ Hi Iarkwiot, and welcome to Puzzling.SE. A common challenge new users are facing with is that they tend to be nervous if their puzzle is not solved within 5 minutes - 1 hour - 1 day, so in a relatively short time. I suggest you not to worry about that. You did your part: prepared a puzzle, laid down some clarifications, and perhaps some hints too. Now it is time to lay back, and... look around, and enjoy other parts of the site. Good luck. $\endgroup$
    – Matsmath
    Commented Nov 26, 2016 at 16:46
  • 1
    $\begingroup$ I didn't downvote your puzzle but it has some problems. (1) You gave a small key for a lot of material (the PDF is 162 pages). You said "no excessive amount of reading" but that's valid only for you because you know what to look for, but another user would be disoriented, so the choices are either read the whole PDF hoping to find something sooner or later, or leave the puzzle. (2) I'm not sure that the symbols being arbitrary is a good thing. That means that there is no particular correlation between 01= and the key, it could be anything. $\endgroup$
    – Alenanno
    Commented Nov 26, 2016 at 17:16
  • 2
    $\begingroup$ Also not a downvoter, but I think it's being downvoted more for bad presentation (huge wall of text) than for being a bad puzzle. If you remove the wall, the code part is not very good because it doesn't have any clues, making it very difficult to solve (see meta.puzzling.stackexchange.com/questions/1717/… ) $\endgroup$
    – ffao
    Commented Nov 26, 2016 at 23:40

3 Answers 3


The password for the second PDF is


First, we can note that as the puzzle says the first PDF leads to a second one,

it probably contains a link to another page. Searching for "http" inside the PDF nets us a link inserted in the middle of the text in page 82, which contains a PNG file.

Thanks to @boboquack for cracking the code that would have helped us find this information:

The code decodes to "twisted lip", which is the title of the story in which the link is hidden.

Take 1->2, 0->0 and =->1, then it is a ternary code with 000-221 as A-Z and 222 as a space.

More directly, this leads us to the address of the second PDF, which is


This PDF, as promised, is locked. Here it may be helpful to notice that

why lead us to a PNG with the link instead of the link in the first place? Probably because there's something else to this PNG...

And indeed there is, as we can find

that the PNG file is, in fact, two PNG files concatenated into one. Inside the second file is a new code: https://i.sstatic.net/smoVr.jpg

This code is a simple substitution using prime numbers (2 = a, 3 = b, 5 = c, etc), yielding the password "phantasmagoriccaprices".

  • $\begingroup$ I was trying to manipulate brightness/contrast and look for metadata in the image $\endgroup$
    – Hurda
    Commented Nov 28, 2016 at 18:48

Partial Progress

This is an expansion on Hurda's answer:

The next PDF is here.

The code resolves to:

twisted lip

Take 1->2, 0->0 and =->1, then it is a ternary code with 000-221 as A-Z and 222 as a space.


A link is in the chapter 'The Man with the Twisted Lip', on page 77 of the book / page 81 of the PDF. The link is to here, giving the tinyurl link to the locked PDF.

Now we need:

A password!

  • $\begingroup$ Very good, I see @ffao used this to solve it. What comments do you have on the 0=1 code? $\endgroup$
    – larkwiot
    Commented Nov 28, 2016 at 14:03
  • $\begingroup$ @larkwiot maybe next time spoilerise the hints and don't release them as quickly. It is a common code, so someone would have found it eventually. Next time maybe try not to let someone take a shortcut that was that obvious-you could use a captcha-like picture so the computer can't find the words with a simple search. What was the intended motivation for finding that there were two PNGs in the one file? $\endgroup$
    – boboquack
    Commented Nov 28, 2016 at 20:14
  • $\begingroup$ I'm not sure what you mean by your question. I am taking notes of your tips though. $\endgroup$
    – larkwiot
    Commented Nov 28, 2016 at 20:43
  • $\begingroup$ @larkwiot Usually in puzzles every non-obvious step has a clue e.g. if I were to make a puzzle where you had to use morse code on the letters I and O I might clue something like ditdah.io or some such thing. What was that thing for the png step? $\endgroup$
    – boboquack
    Commented Nov 28, 2016 at 20:47
  • $\begingroup$ There isn't one. To cover for it though, I could say that every resource or step of the chain is used once. Following that methodology, the imgur would be the only valid thing to investigate to crack the PDF. $\endgroup$
    – larkwiot
    Commented Nov 28, 2016 at 20:50

I have the second PDF, now I need to use my fairly intermediate-to-advanced knowledge of computers to also find the code.

Abstract says that if we know what to look for, we don't even need to crack the code, so I just searched for "http" in the Sherlock pdf (but it feels lame)

  • $\begingroup$ I knew I wasn't crazy for thinking someone might know what to look for. I assure you though, that the next bit should not be lame, if you find it. $\endgroup$
    – larkwiot
    Commented Nov 26, 2016 at 23:37
  • 1
    $\begingroup$ Welcome to Puzzling! Could you possibly explain this answer a little better? I'm struggling to understand what you've done here. $\endgroup$ Commented Nov 26, 2016 at 23:39
  • $\begingroup$ He searched within the PDF given. Does that explain it? $\endgroup$
    – larkwiot
    Commented Nov 26, 2016 at 23:41
  • 1
    $\begingroup$ When you said "[...] so I searched"... how does that follow? [Spock's voice]I don't see the logic in that.[/Spock's voice] $\endgroup$
    – Alenanno
    Commented Nov 27, 2016 at 13:31
  • $\begingroup$ So, you searched for "http", because? $\endgroup$
    – Sid
    Commented Nov 27, 2016 at 15:01

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