Fahrenheit 451 section 3

This section is a little interesting. There are a lot of  thing happened in this section. Milred betrayed Montag and Beatty forced Montag to burn his own home. But I am confused about Beatty's action. Why did he make Montag to kill him? And his history is still mystery. It seens like he know a lot of thing. The rest of the story is a little boring.