Mr. Dunworthy wasn’t listening. He was staring at the tech, who’d come in carrying a black leather jacket covered with metallic slide fasteners. “What exactly is that?” he demanded.

“A motorcycle jacket. You said something in your size,” she added defensively. “It’s from the correct historical era.”

“Miss Moss,” Mr. Dunworthy said in the tone that always made Colin wince, “the entire point of an historian’s costume is that of camouflage-to keep from drawing attention to himself. To blend in. How do you expect me to do that,” he gestured at the leather jacket, “dressed in that?”

“But we have photographs of a jacket like this from 1950…” the tech began and then thought better of it. “I’ll see what else I’ve got.” She retreated, wincing, into the workroom.

“In tweed,” Mr. Dunworthy called after her.

“Blending in is exactly what I’m talking about,” Colin said. “There are all sorts of historical events where a seventeen-year-old would blend in perfectly.”

“Like the Warsaw ghetto?” Mr. Dunworthy said dryly. “Or the Crusades?”

“I haven’t wanted to go to the Crusades since I was twelve. That’s exactly what I’m talking about. Both you and-” He caught himself. “You and everyone at school still think of me as a child,” he said instead, “but I’m not. I’m nearly eighteen. And there are all sorts of assignments I could be doing. Like al-Qaeda’s second attack on New York.”

“New-?”

“Yes, there was a high school near the World Trade Center. I could pose as a student and see the entire thing.”

“I am not sending you to the World Trade Center.”

“Not to it. The school was four blocks away, and none of the students got killed. No one was even injured, except for the toxins and asbestos they inhaled, and I could-”