Found 'scroll of the finder' in the HMV shop, it just looks like a big yellow question mark.

p.s. The item was pretty cool. Too bad that PC died!

Possibly related: in my next character I came across a scroll shop, and this time it is the _scroll of repair_ that lacks a tile (big white question mark instead of picture). I haven't found the scroll of finding yet to confirm, but it sounds like a mismatch between the number of scrolls in the game and the number of tiles.