At the end of part two of "The Sieve and the Sand," in Ray Bradbury's Fahrenheit 451, the fire company truck stops in front of Montag's house. The very last line of the section shows that this is a surprise to Montag who has not been paying close attention to their destination. He has, however, been watching his boss, Beatty, who has been watching him with suppressed excitement.
Montag has been thinking about the best way to stay out of trouble, particularly because he was reading poetry earlier that day to his wife and her friends. In a society where books are banned, and he is a fireman whose job it is to destroy houses with books, he figures he has been flirting with disaster. He has just asked himself...
When would he stop being entirely mad and be quiet, be very quiet indeed?
However, whether he knows it or not, his time is up. Montag first notices that Beatty is driving—very unusual. Whereas Montag has been wondering how he will be able to stop act entirely mad, Beatty seems to be something of a lunatic himself.
"Here we go!"
Montag looked up. Beatty never drove, but he was driving tonight, slamming the Salamander around corners, leaning forward high on the driver's throne, his massive black slicker flapping out behind so that he seemed a great black bat flying above the engine, over the brass numbers, taking the full wind.
"Here we go to keep the world happy, Montag!"
Beatty's pink, phosphorescent cheeks glimmered in the high darkness, and he was smiling furiously.
Beatty is driving and Montag has to wonder subconsciously why. He is also driving like a madman, and Montag imagines that he looks like a huge bat—a creature of the night, stealing life—evil personified. He seems to float above the brass numbers of the engine, hiding perhaps the glimmer of light that might be reflected by the brass, perhaps alluding to evil trying to diminish the light of goodness shining in a world of darkness. Then Montag notices that Beatty's cheeks are almost glowing in the dark, something else quite unnatural, and that he is grinning "furiously." Madness seems to sit at Beatty's fingertips. (And based on how he acts at the start of the next section, perhaps it does.)
There are two ironies at the end of this section. Montag, without looking up to see where he is, has decided that he can no longer live a lie: he does not have what it takes to burn down houses, not with what he has learned about life (through Clarisse) and discovered by reading.
I can't do it, he thought. How can I go at this new assignment, how can I go on burning things? I can't go in this place.
This is ironic for two reasons: on the night Montag decides he cannot burn another house, he discovers to his amazement that he is sitting at his own address.
This is also ironic in that the fireman sent to burn another house has been sent to burn his own house.
Beatty was watching his face.
Once again, the sense of madness is present in the character of Beatty. Throughout the ride and now at their destination, Beatty is unnaturally preoccupied with Montag. At the end he is watching Montag, like a scorpion watching his poisoned prey realize it is about to die—Beatty wants to see how Montag will react to the realization that the house the men plan to burn tonight is Montag's.