Okay, I have this question. First time taking the cryptography course so I have some confusions. First of all, "A Brilliant Detective" part does it mean anything ? I mean, Does it refer to something ?
Also, as far as I am concern decryption should be using the following argument in order to find how substitution cipher works : P(PlainText) = C(CipherText) - K(Key) Mod26
But how can I find the K in this equation ?
As V is the most common letter in the ciphertext, it may well represent E because E is the most common letter in English. That would give $5=22-K, K=17$. Try that $K$ and see if the text comes out readable. If not, try S and X for E. One of them will probably work. The removal of "the" from the text has changed the letter distributions so A or I may be the most common letter.
An easy way to check is a spreadsheet. Put the numeric equivalents of the first fifteen or twenty letters in the A column. Use the next $25$ columns for each of the possible values of K and translate the numbers back to letters. Only one column will read properly.