It looked like any other piece of correspondence but he knew this was different. This was the secret letter he’d been waiting for in moody silence for weeks.
The envelope was plain, the contents unremarkable. He knew to get the real message he must soak off the stamp.
He turned on the kettle and, as it came to the boil, dangled the envelope over the spout in the jet of steam. To his huge disappointment, the stamp was bare. There was no code to be revealed.
“Oh well,” he thought, and used the water to make a cup of tea.