The 87th Passenger Part 3

Sooooooooooooooooooooooo sorry for the delay!! Actually, I was too lazy to write :p

"W...... what?" Nancy stuttered. Cold blood rushed through her body. Luna still stared suspiciously at the note. "But how did the thief manage to do that, even without us knowing?" Luna said deep in thought. "Hmm.... let's see..." Nancy, this puzzle is really simple." Luna smirked, showing her the note. "See. 

"3 1 12 9 6 15 18 14 9 1"

if we observe, the first letter in the series is 3. Then, it's 1. The 3rd number in the series is 12. If we continue this all until the end, we see that if we replace the alphabet which replaces the number in the alphabet series, it makes a word. Suppose, 3. The 3rd letter is c. The first letter is a. The 12th number is l. This whole series of letters make the word: 'California'." 

Nancy gasped. "That means.... the thief is giving us clues of the next place he is going to." "Exactly. And that means... we will have to go to California for the next clue!" 

Again, I purposely made it short. Firstly, to maintain less screen time, and secondly, to keep the suspense. Bye, see ya later!!

Note: The girl on the Cover page is Luna. :p