First, you need to get a rogue stone. If you're far enough in the game to be able to take on the twisted rune, you will probably have seen a few of these.
With rogue stone in inventory, go to the Bridge District. The house in this district that you want is the one just to the right of the kidnappers' house. There are two doors - the one you want in this instance is the right-hand door.
Happy hunting
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