Knockturn Alley

Knockturn Alley is a dark and seedy alleyway in London to which Muggles have no access, and which is frequented largely by Dark Wizards. Many of the shops in Knockturn Alley are devoted to the Dark Arts; the largest is Borgin & Burkes, which sells sinister and dangerous objects.

If your curiosity peaks you may try to enter but look out for other wizards who may see and tell your parents.

As they are walking around the shops, Perpetua sees a street vendor on Knockturn Alley and asks her dad to escort her. They approach the vendor and look over his goods. After negotiating a decent price they decide on buying a Write Answer Quill, which he assures will only write a right answer.

Rabastan is skeptical but buys it anyways.

They return to Diagon Alley and continue shopping.