In Part I, we are introduced to Montag, a man who has kept the status quo for ten years. During this time, he has been a fireman. In this dystopian future, firemen burn books and the homes of those who house books. This is all a social strategy of preventing people from thinking too much in order to prevent anxiety and any uncomfortable thoughts. Most people go along with this social planning because they are numbed by drugs and mindless entertainment. Montag's wife, Mildred, is one of these people. This first section of the novel is about Montag's intellectual awakening from this socially-induced slumber.
Walking home, he meets Clarisse, a free-thinking young girl who helps spark Montag's awakening. She makes him think critically and question things. She even suggests that firemen used to put out fires rather than start them. Such thoughts stay with Montag. After meeting her, he returns home to find that Mildred has overdosed on sleeping pills.
Montag's talks with Clarisse make him increasingly interested in questioning his society and his interest in books increases as well. During this time, he becomes unable to get Mildred to have the same thoughts. She would rather remain thoughtless and complacent like most of the brainwashed masses.
Montag is quite affected when the firemen respond to an alarm about a house full of books because the woman living there chooses to burn with the books. Mildred is unaffected by this when Montag explains it, and this widens the distance between them. Clarisse eventually disappears and indications suggest that she had been removed and/or killed by the authorities for being too inquisitive.
Montag even questions his boss, Beatty, about firemen in the past and books in general. Beatty tries to quell Montag's curiosity but it does not work. The first part ends when Montag reveals to his wife that he has been hoarding books in their home. When the alarm tells them someone is at the front door, Montag and Mildred are afraid that it might be Beatty.