Captain Beatty dies when Montag aims the flame thrower at him and burns him alive.
In the course of their work in burning books, Beatty leads Montag straight to Montag's own house. As they stand at the front door, Montag's wife, Mildred, comes running out with a suitcase in her hand. At the same moment, a taxi screeches to the curb to pick Mildred up. Montag is shocked and grieved that Mildred may have been the one to give the alarm about the presence of books in the household.
Meanwhile, Beatty taunts Montag about the nature of fire and how the real beauty of fire is that it "destroys responsibility and consequences." He hints menacingly at getting rid of Montag with fire:
Now, Montag, you're a burden. And fire will lift you off my shoulders, clean, quick, sure; nothing to rot later. Antibiotic, aesthetic, practical.
Dazed and maddened by his wife's betrayal, Montag snaps the safety switch on the flamethrower and proceeds to burn up everything in his house. Beatty tells him that, when he is finished, he will be arrested. Montag again asks whether it was Mildred who betrayed him. The Captain answers that her friends had betrayed him long before she ever did; he assures Montag that, one way or another, he would have been caught eventually.
Beatty continues taunting Montag, but Montag is still stunned that the life he and Mildred shared has just burned up in front of him. Eventually, Montag turns the flame-thrower towards Beatty. Beatty mocks him once more about being a "second hand litterateur" and prompts him to pull the trigger. Apparently, Beatty doesn't think Montag has the courage to kill him. As he walks towards Montag, Montag flips the switch on the safety-catch, aims the flame thrower at Beatty and burns him alive.
And then he was a shrieking blaze, a jumping, sprawling, gibbering mannikin, no longer human or known, all writhing flame on the lawn as Montag shot one continuous pulse of liquid fire on him... Beatty flopped over and over and over, and at last twisted in on himself like a charred wax doll and lay silent.