A ring from the locked room
Every day at noon, a bell rang inside the repair workshop. Lena heard it from the bakery next door while setting out the first tray of lunchtime rolls. The sound was brief and bright, always two notes close together. It would have been unremarkable if the workshop's owner, Tomas, had not closed the shop for a fortnight and left its keys with her.
On the third day, she went inside just before noon. A brass handbell stood on the workbench beside a row of repaired clocks. She watched it carefully. At twelve, the familiar sound came from somewhere near the bench, but the handbell did not move. Its clapper was wrapped in felt, tied in place with a scrap of string.
Lena checked the clocks. None had a striking mechanism, and most were waiting for parts. She wondered whether a delivery driver was pressing the shop's doorbell, but nobody stood outside the locked front door. When she opened it herself, the old mechanical bell above the frame made a rough, rattling sound quite unlike the two clear notes.
She wrote down the time and returned the next day with a notebook. This time, instead of watching the brass bell, she stood beside the dividing wall. The sound seemed louder there. On the wall, half-hidden by a calendar, was a small square grille that she had mistaken for a ventilation opening.