Hagar of the Pawn-Shop by Fergus Hume

Hagar Stanley, a beautiful young Gypsy, is driven by sexual harassment to leave her tribe and seek refuge with her uncle Jacob, a miserly London pawnbroker. He dies after teaching Hagar the business, and she takes over running the popshop till the legitimate heir can be traced. In the odd assortment of objects that pass across her counter, Hagar uncovers one mystery after another. Some items are linked to actual crimes, others to iniquitous acts of human deceit and betrayal. Whether investigating independently or alongside the police, Hagar combines her native shrewdness with woman's intuition to help untangle the webs of wickedness she encounters, that justice might prevail in the end. Though the individual mysteries in Hagar of the Pawn-shop may be read separately, they are so arranged by Fergus Hume as to form a linked set, with characters from earlier stories popping up again later on, one as Hagar's love interest and another as her nemesis.