Gold filigree heart with keyhole and key

The old keyholes in the Deep were cut in the shape of hearts with the lace pierced right through, and the metal was gilded so it caught lamplight and threw it back in flecks. Ines said the first makers used leaf because it would not tarnish underground, and because a key cut from a lock's own pattern would open that lock and no other. She had kept one blank for forty years, a key with a heart for a bow and a cross in its bit, and she would not let me touch it.

We worked the door through the night. The probe went in, then the rake, and at last Ines slid the gold blank into the keyhole and turned it with two fingers, slow as a clock hand. Something inside the frame let out a breath of cold air that smelled of cut stone and pressed flowers. Beyond it was no vault but a corridor of shelves, each holding sealed tin boxes, every lid stamped with a small diamond.

She lifted one down and read the label aloud. It bore my name, in a hand I did not recognise, and a date four years from now. Ines closed the lid, pressed the key into my palm and said the door opened only once for each person, so I had better decide what I wanted to find before I turned it again.