“Nothing jumps out,” Theo said. “But it could be hidden the way all the other ciphers have been hidden. Invisible ink, or maybe there’s an address on every third page or—”

Tess cut him off. “Or every fifth page or maybe there’s something hidden in the binding or glued to one of the pages.”

“Yes, but I think if—”

“Or maybe if you take the first figure of every page and add them or multiply them or divide them, you get a number of a house somewhere in Brooklyn or the East Village or something.”

“I—”

“Or maybe we went to the wrong house and stole the wrong book. Maybe we were never meant to follow the robot at all. Maybe it’s a decoy built by the Morningstarrs’ greatest nemesis.”

Theo pulled his lip. “Who was the Morningstarrs’ greatest nemesis?”

“Take your pick. Charles Dickens. Charles Babbage. Any Charles. All the Charleses.”

“Why would all the Charleses—”

Jaime put a hand on Theo’s arm to stop him, to save him from pitching himself into Tess’s endless questions, her endless possibilities. “The puzzles are always hard at first,” Jaime said to Tess. “But we’ve figured them out so far. And didn’t you say that the Cipher is figuring us out, too? That maybe it wants us to understand it?”

Tess got to her feet and moved to the window. She hooked a finger around the curtain and peeked out at the postage-stamp-sized backyard. “That was before.”

Theo stopped pulling on his lip. “The Cipher didn’t take Nine. For all we know, solving the Cipher has nothing to do with Nine.”

“Her name was a clue!” Tess said. “And why else would anyone lie about her? Why would someone say she was a machine and not a real animal? The Morningstarrs designed all the machines. And they also created the Cipher. What if someone has figured out what we’re doing? What if that someone wants to stop us from solving the puzzle?”

Jaime said, “Are we going to let them?”

Tess pinned him with dark, angry eyes. “And weren’t you the one who said that we should lie low for a while?”

“Yes,” Jaime said. “That was before.”

“Before what?”

Before they made me feel small. “Before they took Nine.”

The little robot marched into the open closet and tipped headfirst into a sneaker. “Oh no,” it said.

“‘Oh no’ is right,” said Tess. The anger in Tess’s face dulled and she let the curtain drop. She sat back on the floor.

“Okay. So let’s look at this thing one page at a time. Theo, where’s your magnifying glass?”