Liam’s whole face lit up. “Yeah! I can show you the formulas. The energy passes between universes—there may be other dimensions, but our world seems to have the closest link to—”

“I wonder how it affects Kepler’s gravitational equation—”

“I wondered that too. I can pinpoint the years when Sicarelli’s bridge was open. It’s all observable in interstellar background radiation—”

“Enough, both of you!”

Simone glared at Phillip. He at least should know better. He had a mission, same as her. Phillip hung his head, chastened, but was still grinning with giddiness over a new scientific puzzle to solve.

“So there are the monsters—those come from the other side. As does this energy you use. But what about when it seems to possess people?” Simone asked. “Like those guards that were chasing you.”

“That’s what can happen when the energy works its way inside someone, corrupting them from the inside out. People who are already angry, hateful—the darkness has an easier time attaching to them because they’re primed for its corruption.”

“Like the Nazis,” Rebeka said.

Liam nodded, eyes narrowed. “Like the Nazis. As the energy suffuses them, they become stronger. Even more dangerous than they already were.”

Simone pinched her nose, trying to fight back the tidal pull of her own anger. “And you want to meddle with these forces, why, again?”

“Because of what that power can do. You’ve seen what I can do by myself, wielding it. Now imagine that on a massive scale. How it could help the Allies turn the tide of the war.”

“Or make the Germans even more powerful,” Simone said.

Liam’s head slumped. “Which is why I need to get Sicarelli’s book away from them. The book—it’s the key to drawing on an unlimited amount of that energy instead of the slow drip I can manage on my own. He supposedly stabilized a bridge between the two universes for a brief time, which means we can do it again.”

Fine. She’d seen the results of this shadow world clearly enough, if not the world itself. The darkness that wore human skin, the shadows that slithered and screamed, and plenty of other kinds of monsters besides. There was no use denying it was real. But just because this boy could do these things didn’t mean she wanted him on their side.

“The monsters. They were hunting you.” Simone rubbed at her temples. “They were calling your name. Why?”

Liam went quiet at that. Of course. He drummed the fingers of his uninjured hand against his knee, a bundle of nervous energy. “Our universes . . . have a history,” he said carefully. “They resented Sicarelli for meddling in their world. I’m sure they feel the same about me.”

“So by being here with us . . .” Simone cast her gaze around the balcony turned projection room. “You’ve put a target on our backs.”