Ash squinted down at the squiggles and scribbles. They could’ve been written in ancient Greek for how well he understood them, but he frowned, thoughtfully, and scratched his chin. He could feel Zora at his shoulder, practically vibrating as she waited for him to say something.

Finally, he said, “Can you just tell me what I’m supposed to be seeing here?”

“Oh, right. Okay, so you see this number here?” She pointed to a scribbled line of digits that looked like a phone number.

Ash nodded.

“This was recorded after my father’s first trips back in time. And these, see how these figures keep going up? They’re moving in relation to the frequency and length of the trips my father has taken. It never occurred to me to try to match them all up before, but look here.” There was a pause, while Zora waited for Ash to see what she saw. “They fit, perfectly. See?”

Ash frowned. “Zora, I’m going to need you to just tell me what you’re trying to say.”

“Seattle’s on the Cascadia Fault, right?” Zora layered her hands one on top of the other, so that her knuckles were aligned. “It looks like this. Every time we go back in time, there’s a tremor.”

She moved her hands so that her knuckles bunched together. “The tremors do this to the fault line, right? So the more it happens, the more the energy builds up and the fault line gets all cranky and then—”

She snapped her hands into a fist. “Earthquake.”

Ash felt a sinking in his gut.

Zora said, in a rush, “I started thinking about it when we watched the Black Crow go through the anil. Remember how the earth trembled? Like there was going to be a quake?”

“There are tremors all the time now,” Ash said.

“Exactly,” said Zora. “Because the Black Cirkus has been using the anil more frequently. And if you look back at the earthquakes that were largest, historically, they all match up with the patterns of my father’s travels. I never put it together, before, because it’s not like we go back in time and then suddenly—bam—there’s an earthquake. But each trip through time brings us closer to the next earthquake. See?”

She pointed and, this time, the lines of notes and numbers made a little more sense. Ash recognized the dates when they’d gone back in time, the magnitude numbers used to quantify the scale of an earthquake. His head started pounding, a deep, steady throb that made his eyesight go bloody.

“That can’t be right,” he said. “The Professor would’ve noticed.”

“Dad was always inside the time machine when we went back, so he wouldn’t have noticed the tremors. And it’s like I said, this sort of energy takes time to build up. By the time the earthquakes finally occurred, they seemed random, but . . . but they’re not.” A breath, and then, “The earthquakes are caused by time travel. They’re caused by us.”