Answer:
In Ray Bradbury's novel "Fahrenheit 451," when Captain Beatty sees Montag in the firehouse, he doesn't ask for anything verbally, but he makes a subtle gesture by tapping his fingers against his thigh, which conveys his request for Montag to hand over the book he's secretly hiding. This is a non-verbal way of signaling that he knows Montag has a book and that he wants it surrendered for destruction.