“Remember the treasure hunts he used to set up for us?” I asked them, jumping up from the table. I got my leather-bound journal and a pen and sat down again.
“Of course,” Zander said. “You think he left us a code?”
I didn’t answer. I was already searching the little doodles.
The first thing to do was find a word I could use as a key, that is, a word I could identify because of its length or because of the repetition of a particular letter or letters. For example, a word like Mississippi was a good key. Say you’d created a code where a different letter stood in for each letter. If you saw Tfjjfjjfyyf, you could figure out that T stood in for m and f stood in for i and so forth, because there were no other words with that exact pattern of repetition.
But Mississippi was a dead giveaway. Anyone who knew anything about codes would recognize it. Dad—if in fact Dad had written the message—would have used something that only we would understand. And this code didn’t replace letters with letters, it replaced them with symbols.
I pushed my glasses back up on my nose, wrote the whole thing out on a clean page in the journal, and started studying the combinations of symbols.
“I’m looking for the key,” I told them.
“Maybe it’s one of our names,” M.K. suggested.
My name and Zander’s wouldn’t be much help, as they didn’t contain any repetition of letters and weren’t abnormally long or short. M.K.’s full name was Mary Kingsley, after a famous English explorer. That might help, because of the rarer combination of a four-letter word and an eight-letter one with only the repeated y, but I didn’t see anything that fit.
And then suddenly I thought of Dad in the yard, saying goodbye.
“I think I’ve got it,” I told them. “What did Dad call us? What did he say when he was leaving for Fazia?”
“The Expeditioners,” they said together. The Expeditioners. That had to be it. I had to find a thirteen-symbol word.
I read over the symbols I’d copied and, sure enough, the sixth word formed by the symbols was thirteen symbols long, with the first symbol repeated in the fourth and then again in the eleventh place. So the little eagle symbol was e. I wrote that down. Then I wrote down the symbols for the rest of the letters included in the word.
Now I knew the symbols for e, x, p, d, i, t, o, n, r and s. Slowly, I started working the code, using the same process of elimination you use to solve a difficult crossword puzzle.
Zander and M.K. were absolutely silent while I worked. I wasn’t sure how much time had passed, but when I finally looked up from my work, my stomach was rumbling with hunger. I didn’t care, though. My heart racing, my skin prickling all over with the excitement you feel when something’s about to happen, I read aloud the fragment of the message sitting in front of me:
CAN YOU CRACK THE CODE, EXPEDITIONERS?
THE THIRD OLD OAK ON THE RIGHT FLIPPED