A Bit of Light Reading is a side quest given by Hermione Granger after the completion of the storyline quest, Alohomora. While the game announces it like a traditional side quest, it does not appear in your quest log, or count towards the total number of side quests completed in your Treasure Hunts section. Instead, it serves to open a service where Hermione will buy Rare Books from the player for extra cash.
Conversation[]
Player: Do you need any more help?
Hermione: You're very kind.
I do as a matter of fact; I've worked my way through most of the interesting sections in the Hogwarts library and I'm looking for a bit of extra reading.
Hermione: If you find any interesting or rare books please bring them to me.
I'll page 50 gold for every rare book your bring me.
Player: I will.
How to Complete the Task[]
This quest cannot be "completed" as such. Hermione will buy any Rare Book you bring her for 50 coins a piece from this point on.