The    C HL io H s    Incident   of  

the   Dog   in   the    Night – time

Thinking of common words ending -io?s, you might think of -ions (e.g. scorpions) and -ious (e.g. glorious). Since we’ve already found n, then H most likely stands for U.

The    Cu L ious    Incident   of  

the   Dog   in   the    Night – time

To find H, let’s consider the most likely options.

The most common letters:             E, T, A, O, I, N, S, H, R 

We have found all the above letters in this title, apart from a and r.

Which is right: curious or cuaious?

Yes, that’s it.

The    Curious    Incident   of  

the   Dog   in   the    Night – time

And that is how codes and ciphers are cracked – intuition, trial and error. And persistence.