The War that Saved My Life by Kimberly Brubaker Bradley

The man blinked.
I said, “I would like to speak to your commanding officer. The government
asks us to report anything suspicious, and that’s what I am going to do. If you
won’t listen, I want to talk to someone who will.”
The second police officer took me more seriously. “We’ll go in the squad
car,” he said. “See if we can find him.” He asked if I needed help getting to
the car.
“No, thank you,” I said. I walked as straight as I could manage, even
though it hurt like crazy. The officer put me in the front seat beside him and
together we started down the road. We’d hardly gotten out of town when we
came across the man I’d seen, walking down the road with perfect ease. I
pointed him out to the officer.
“You’re sure?” the officer asked.
For a moment I wasn’t. I hadn’t really gotten a close look at the man’s
face. But he felt like the right person. I nodded. The officer stopped his car
and got out. “Papers, please,” he said.
“Really?” said the man, in perfect English with the accent Lady Thorton
used. “Why ever for?”
“Routine,” the officer said.
The man raised his eyebrow as if it were all a joke, but reached into his
pocket readily enough. He pulled his identity card out of a battered leather
wallet. “I’m just on a bit of a walking holiday,” he said, indicating the
rucksack on his back. “My ration card’s in there if you want me to fish it out.”
He could not sound more English. He could not look more English. And
yet—
“Sir,” I said to the officer. He came over to the window on the passenger
side, and leaned in.
“I’m sorry, miss,” he said, shaking his head, “but I think you’ve—”
I said, “His trouser cuffs are wet. And they’re full of sand.”
No one went on the beaches anymore. No one ever. It wasn’t allowed.
The officer’s smile disappeared. For a moment I thought he was angry with
me, but I was wrong. The next thing I knew the man from the beach was
handcuffed and bundled into the back of the car. He protested vehemently in
his perfect English voice.