“At least I wouldn’t have to sit around at home waiting for another policeman to knock at the door.”

“If we could only find Carl’s rifle,” Aunt Sal said.

It was out there somewhere. Instead of getting ready for baseball tryouts when the bus let him off after school, Nate would choose a section of field and pace its length, hoping to catch sight of it. But for all his searching—the hours he spent walking their land, eyes to the ground—it seemed as if the earth had simply opened up and swallowed the thing.

The rest of the time, he and Naomi worked on their science fair project. Ideas for how to make it better came to him at odd times throughout the day and even in the night. Shortly after his talk with Frank, Nate had revised his thought about not needing a depressurizing gauge for the cloud chamber. Since then they’d been struggling to make theirs work, without compromising the seal on the chamber itself. He’d called Naomi up one night at nine thirty—late enough to wake her dad—to tell her a new idea.

“I’ve been worried the flashlight beam just won’t be strong enough to make the tracks of the alpha and beta rays show up,” he said. “But I figured out what our light source can be. My uncle’s slide projector.” He said it like some old-time prospector who’d just found gold in his pan.

“What’s got into you, anyway?” Naomi asked him the next day. They were sitting in the cafeteria together, and he was talking about how it would be, once they had the dry ice and they could run their actual test.

“I just decided we’re going to have the best science fair project ever, that’s all,” he told her.

Even though the science fair was still more than a month away, every day that they had to refine their cloud chamber suddenly seemed precious.

Naomi was in charge of the written report and the drawings for their poster. Both of them worked on the actual construction of the cloud chamber, but Naomi understood that was more Nate’s department. He wanted the box to be perfect before they did their dry run. At the moment they had glue drying on the rubber seals, and nothing much could be done until it set. And the dry ice had to come from Chicago—something that needed to happen as close to the date of the science fair as possible.