The Bell and the Borrowed Stamp

The book-repair room at Ashwell Library is yours for exactly one hour before Head Librarian Oswin returns from her trustees' lunch. You are not supposed to be here. You are definitely not supposed to have borrowed the rare Vermillion Wax Seal that lives in her top drawer. But the antique Society of Bookbinders certificate on the drying rack needs it — and the noon bell will ring in sixty seconds, which is when Oswin always walks back through that door. The trick: the seal only bonds to paper when the wax is hot, and the repair-room kettle whistles exactly at noon. Miss the whistle and the wax sets cold. Wait too long and Oswin catches you in the act.