They bind you to the chair. They put a thumbscrew around your thumb. The torturer turns the screw. Slowly. The pressure becomes uncomfortable.
The magistrate says, "You may confess at any time."
The torturer again turns the screw. Slowly.
Pain begins, becomes sharper, becomes horrible. You once felt such pain when you hit your thumb with a hammer. But this pain just goes on and gets worse. You watch your thumb squeeze out of its normal shape and turn purple. The nail begins to buckle.