It was a good question. Hermione was sure they were right about the initials. Regulus had been a Death Eater, they were sure, and he’d disappeared. It fit. But actually finding the locket here somewhere in the house was another story. Clues, perhaps, in his room? Or …
A door slammed upstairs, and she pursed her lips as she looked that direction. "Kreacher?" She asked, frowning. "You don’t suppose he’d know." But once she’d said it, something clicked, and her eyes went wide as she turned to look at Ron and Harry. "That cupboard he was always guarding upstairs. With his treasures. Things that that the Blacks left behind and he horded away. What if it wasn’t only things Sirius’ mum left? What if there were things from Regulus there too?" And even as she said it, it felt like the answer, and Hermione turned to rush up the stairs, with Harry and Ron close behind.
She barely noticed Kreacher as she went into the room, but when she went to throw open his cupboard she was surprised to find it nearly empty. She was sure there had been more there when she’d managed a peek inside before.
"Kreacher!" She turned to find the elf in the corner, looking livid but also shaking. "Where are the things that you kept here?"
To Hermione’s surprise, Kreacher closed his eyes tight and began to cry.
"Mundungus Fletcher," croaked the elf after a few silent sobbing moments, his eyes still tight shut. "Mundungus Fletcher stole it all; Miss Bella’s and Miss Cissy’s pictures, my Mistress’s gloves, the Order of Merlin, First Class, the goblets with the family crest, and – and – " Kreacher was gulping for air: His hollow chest was rising and falling rapidly, then his eyes flew open and he uttered a bloodcurdling scream. "—and the locket, Master Regulus’s locket. Kreacher saw him!"