Where does Montag stop before he goes to Faber’s? What does he do while there?

Montag stops at the Black's home to plant books.... setting Black up for the same thing he'd repeatedly done to others.

Mrs. Black, are you asleep in there? he thought. This isn't good, but your husband did it to others and never asked and never wondered and never worried. And now since you're a fireman's wife, it's your house and your turn, for all the houses your husband burned and the people he hurt without thinking.