forty-eight constellations described by the ancient Greek astronomer Ptolemy were drawn and starred in silver inks. Crater, Lyra, Orion, Cassiopeia, all the others. Evenly spaced around the map’s edge was a sequence of letters in gold forming an incomplete alphabet, which had always puzzled Wade and about which his father had offered no real explanation.
“Okay, so,” Dr. Kaplan said, taking a deep breath. “First we have the email.” He produced the printed email from his blazer pocket, then carefully traced his fingers over the letters bordering Wade’s star map. “Uncle Henry gave you this chart for your birthday, knowing you would like it.”
“I love it,” Wade said almost reverently. “It’s what really got me super-interested in the stars.”
“I know,” his father said. “Maybe you don’t remember me telling you, but it wasn’t the first time I had seen this map. Heinrich showed it to me while I was still a student, quite a few years before you were born. He had a little apartment then; he still does.”
“Have you seen him since then?” Becca asked.
“Once, then letters, email once in a while,” he said. “Heinrich had always been a collector of antiques. One night twenty or so years ago, in front of me and some other students, he unfolded five identical printings, all hand-colored, of the same map from the sixteenth century. This map. As we all watched, he took out a pen, dipped it in gold ink, and without a word, inked an alphabet around the edge of each one.”
“But the alphabet is messed up,” Lily said. “It’s only got … seventeen letters.” On her tablet she typed in the gold-inked letters framing the star map, while Darrell did the same on a yellow pad.
C D F G H I J K M O P Q V W X Y Z
“Of course.” Dr. Kaplan slipped on a pair of reading glasses. “We noticed the same thing. Heinrich told us our alphabets were one part of a cipher—a code—of his own invention. He said we might have to use it someday. Before we ever needed it, he said, he would see that we each received one copy of the map. Then he put them away before we could really do any figuring. And that was that. I never thought much about the maps again until your seventh birthday, Wade, when he gave you this one. He brushed off any mention of the code then. I assumed it didn’t matter anymore.”
Darrell shook his head slowly. “But it does matter. And it proves I was right. He was a spy. He was pretending to be a professor, but he was a secret agent.”
Dr. Kaplan cracked a smile. “I really don’t think so. He’s retired now, but he was one of the foremost physicists of his day. When he first showed us the maps, he swore us to secrecy. He called our little group of five students Asterias. That’s the Latin name for the sea star. We were, Heinrich said, like the five arms of the starfish, and he was the head. It seemed a little silly at the time. A professor’s whimsy. But we were graduating and going our separate ways, so we all agreed. In the last few years I lost communication with most of them, and he’s never asked me to use the code. Until today.”
Wade breathed in to try to calm himself. It didn’t work. A hundred questions collided in his brain. “Are you saying that the cipher on the map will decode the email?”
“But not all the letters are there,” said Becca. “If it’s a standard substitution code, it needs all twenty-six letters.”
Everyone looked at her.
“Substitution code?” said Darrell. “Uh-huh. Putting aside for a moment what substitution codes even are, how do you know about them?”
Becca blushed a little. “I read. A lot. Last summer I read all the Sherlock Holmes stories. You know what I mean, right, Dr. Kaplan?”
He smiled. “I do. Sherlock Holmes solves substitution codes in several of the stories. When we asked Heinrich about the missing letters, he just winked and slyly tapped the side of his nose. We pressed him about what he meant, and he said, ‘when things are missing, you look for them!’ You’re all pretty brainy, so the first step for us is, what letters are missing?”
Lily had apparently already figured it out and told them with a grin. “A, B, E, L, N, R, S, T,
“Good,” Dr. Kaplan said. He wrote them on Darrell’s pad.
A B E L N R S T U
“Nine letters. The cipher begins as a fairly simple Caesar code, a substitution code originated a couple of thousand years ago by Julius Caesar for his private letters. Heinrich was a student of ciphers, and he modified this in his own way.
“So, the letters not on the map form a secret word or phrase. You unscramble the missing letters to find the words, then put them at the beginning of the alphabet to make the full twenty-six letters again.”
“Nine letters could spell a lot of words,” said Darrell.
Dr. Kaplan nodded. “But they should somehow be familiar to the person for whom the code is intended …” He paused, stroking his chin. “My diary. I kept a journal then, a student notebook, where I wrote down lecture notes and random things. It’s in my office. Hold on.” He left the room at a trot.
“We can start,” said Becca. “A, B, E, L, N, R, S, T,
The dining room went quiet, except for Darrell’s pencil scratching and occasional humming and Lily’s fingers tapping on the tablet’s screen. Becca frowned and looked off across the room.
Wade tried to think, but the image of Uncle Henry inking the maps in gold was mesmerizing. Was it by candlelight, their student faces glowing? Was his apartment as hushed as their dining room was right now? Why did he do it in the first place?
His father returned, leafing through a small black notebook. “Maybe the answer is somewhere in here …”
“I get the words rest, nut, and eat,” Darrell said finally.
“Of course you do,” said Lily. “I see ears.”
“I get lean burst,” said Becca with a smile. “Do I get a prize for using all the letters?”
Wade resisted jumping up and shouting, “Yes, you do!”
But the more he studied the letters, the more they began to shift places like the panels in one of those number slide puzzles. This was how his mind often solved math problems. His father said he was a natural at numbers. And now, apparently, at letters, too.
Common combinations … S … T … slid forward and back … vowels moved and moved again. Fixing his eyes on the letters, Wade went through them again, again, then click. Solved. Or sort of solved. He
Four faces looked at him.
“One thing the letters spell is blue star with an extra n,” he said. “I don’t know what the n stands for, but a blue star is a real thing. If a star appears blue, it means it’s approaching Earth.”
Dr. Kaplan stared at the letters on the pad, nodding. Then he turned to the last page in his notebook and smiled. “Oh, boy. Close. Very close. But look.”
As they watched him, he slowly rewrote blue star n as blau stern.
“Blau stern?” said Becca. “That’s blue star in German.”
“Exactly,” Dr. Kaplan said, showing them the words in his notebook. “Blau Stern was the name of the café in Berlin where we met after classes—”
“I knew it!” said Darrell. “Your spy hangout!”