“There are certain letters in the English alphabet that are used more often in English words than other letters, like e and a. If this is a substitution cipher, and we figure out how often each letter appears in this cipher, we might be able to figure out what it says. There are tools on the web to do the calculations.”

While Theo found a tool and punched in the characters from the cipher, Jaime lay back on the rug with his hands behind his head, thinking. Any other day, Jaime might have been excited about Theo’s suggestion and eager to see what the tool came up with. And yet, though the food had made him feel better, he still got the feeling they were missing something obvious, that they were taking the long way around when there was a simpler solution. He mentally retraced the steps that had gotten them to the library in the first place. Lovelace, Babbage, the Analytical Engine, the—

Wait.

“Babbage!” he blurted.

“What about him?” said Theo.

“When we read about him before, wasn’t there something about him solving a specific kind of cipher?”

Tess grabbed his wrist. “Yes! But I can’t remember what it was called.”

Quickly, Jaime searched for the terms Babbage, cipher and found what he was looking for. “The Vigenère cipher,” he read, sounding out the unfamiliar word. “To encipher a message, you use twenty-six different cipher alphabets instead of just one.”

Theo stopped what he was doing. “Really? That’s awesome.”

“Here’s a table with the different alphabets,” Jaime said, holding up the phone. The twins leaned in to look:

“That is cool,” Tess said.

“The problem is that we need a key word in order to decipher the message,” Jaime said.

“Whomp-whomp,” said Tess.

Jaime checked the time on his phone, stood, stretched. “I’m going to be late for dinner if I don’t get going. Work on this tomorrow?”

“Tomorrow,” said Tess, holding up her fist. Jaime bumped it. Theo saluted. Nine wound herself around Jaime’s legs three times, as if she were casting some sort of spell. Maybe she was.

Jaime walked down the stairs and found Aunt Esther watering her plants while the mechanical spiders darted away from the streams.

“Jaime!” she said. “I thought I heard your dulcet tones wafting down from the attic.”

Jaime laughed. “I don’t think anyone’s called my voice ‘dulcet’ before.”

“They should,” said Aunt Esther. “Back when I was a casting agent, I heard plenty of non-dulcet tones, believe me.”

“When was that?”

“Oh, years ago,” she said, shooing away a spider. “If you wanted to, you could get voice-over work when you’re older.”

“Thank you. I’ll keep that in mind,” said Jaime, heading for the front door. “Gotta get home now.”

Aunt Esther added, “Or you could keep on doing what you’re doing.”