His voice cracked. He closed his eyes for a moment, seeming to need to regain his composure. A beat later, he continued, “After Natasha, it seemed important to figure out why they were happening, maybe even find some way of predicting them in the future. Years ago, Roman had been looking into that sort of thing, studying tectonic-plate and fault-line activity. He’d even built some computer program that was supposed to predict how the earth’s crust might move in the future, but he’d given all that up when I recruited him to our team. I went back in time and borrowed his research, to see whether he’d been onto anything.”

“And he was,” Ash guessed.

“Oh, yes.” The Professor lifted his eyes. “I’m not sure Roman himself was fully aware of what he’d discovered. There were patterns, you see, numbers that proved there was some correlation between time travel and the earth’s movement. It was all very fuzzy science, of course. Nothing conclusive. But it was a start.

“Once I saw the trends, I couldn’t just look the other way. I had to know more. But the city was still recovering from the flood. I needed resources, a clean place to work, a lab, books . . . I tried to get in touch with the few allies I still had in the Center, but they weren’t interested in helping. The earthquakes weren’t affecting them. And WCAAT, well, all the research we’d spent years developing, everything, it was all gone.”

“So, you went to Fort Hunter,” Ash said.

The Professor nodded. “Once I realized I needed to travel back in time to gain access to the sort of resources I needed, the entirety of human history was open to me. It made the most sense to go back to a time when they were investing in the exact type of science I was looking into. In the 1980s, Fort Hunter spent an enormous amount of time and money delving into the world of environmental modification. The plan was to attempt to weaponize it, I believe, but the program was shut down later that decade after some political pressure. I thought it seemed worth a look, so I went back.

“I only spent a day there, but it was enough. More than enough. Within hours, I was able to verify my theory that the continued use of the Puget Sound anil would only lead to larger and more devastating earthquakes in the future.”

Ash thought of the scrawled notes he’d found on the windshield of the Dark Star, each a date and a magnitude number, the promise of more devastating earthquakes to come.

“So why didn’t you come back then?” he asked, his throat closing up. “You could have helped us. You could have warned us.”