Mistress Natalie, wearing your chastity key around her neck, makes you earn the chance to get unlocked.  Bound in her sex swing with hands shackled and legs spread eagle she teases you with the key.  Her strap-on against your hole, letting you know there will be no release without a good pounding. After fucking your weightless body she stuffs you with her cock tempting you with the key right above your face.  Finally you are unlocked.  BUT with hands still shackled you must learn to cum only through her fucking you with her cock.