He boarded the evening express.
He never got off.

Or did he? One free case file. Your child works it with a pencil.

A Bureau courier got on the 6:05 train carrying a locked dispatch case. Three people swear they saw him aboard. At the end of the line, the compartment was empty.

One of those three sightings cannot be right. Everything needed to work out which is printed on the page — a working timetable, a coded note, and a cross-reference grid. Nothing needs looking up. Nothing needs a screen.

Most children solve it in about forty minutes. A fair number of adults get it wrong on the first pass, which is usually the moment the child stops asking for help.

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What is actually in it

This is not a worksheet with a border round it. Every page is built as an object from the file — a memo with words blacked out, an exhibit tag, a chalked slate. Your child is not completing an exercise. They are handling evidence.

• A briefing memo with redactions. The length of each black bar matches the word hidden under it.
• Two exhibits — a railway timetable and an intercepted note written in a Caesar cipher.
• A cross-reference grid, which is a logic grid wearing a Bureau uniform.
• A field notebook page, because agents who write down what they know solve cases that agents who just remember do not.
• An after-action review — three questions about their own thinking, not about the plot.

That is a real cipher with a real answer, and an eight-year-old can break it with the wheel printed in the file.

Why the last page is the point

Every case ends with a debrief. Not comprehension questions — questions about judgment. What did you assume before you looked? Which clue felt important and proved nothing? Where would panicking have cost you the answer?

One witness in this case is not lying. He honestly reports what he saw, and what he saw was a hat. He decided it was a man. Working out the difference between those two things is worth more than any puzzle in the file.

Why it is free

Because there are nine more cases, and the honest way to sell them is to let you watch a child do the first one at your kitchen table. If they push the page away after five minutes, you have lost nothing and I have lost nothing. If they argue with you about the timetable, you will know exactly what to do next.

That is the whole reason. There is no upsell in the file itself, no account to make, and nothing in it phones home.

P.S. If you teach, the file works as a full lesson with no preparation. The grid does the differentiation for you — the ones who finish early can try breaking the cipher without the wheel. There is a teacher guide, and it is also free. Just reply to the email and ask.