Answer: Secret Code #172

The secret message says:

TIGER

The shift was 20.

The secret note decoded: TIGER
The note, decoded.

Letter by letter

Secret letterACLNY
Real letterGIRTE

Decode it with Python

This program does the decoding for you. Change the secret and the shift to crack other messages!

secret = "NCAYL"
shift = 20
message = ""

for letter in secret:
    if letter.isalpha():
        number = (ord(letter) - ord("A") - shift) % 26
        message = message + chr(number + ord("A"))
    else:
        message = message + letter

print(message)

When you run it, it prints:

TIGER

Did you know? Shift codes are very old. A Roman writer called Suetonius said that Julius Caesar wrote secret letters by shifting the alphabet by three. That’s why it’s often called the Caesar cipher.