The Knock spell scroll is an enchanted item to be had in the undercity for two hundred and seventy-five gold pieces. It lets the bearer cast the Knock spell, which throws open doors and coffers that have been sealed by magic — a thing of no little use to any who would come at a barred quarter or a hidden hoard.
Sidra al-Najjar came upon the scroll whilst browsing the Thieves' Bazaar. She marked its presence, but owned that she wanted the funds to buy it; its availability was noted amongst several other wares, a small proof of its worth to those in the adventuring way.