Consensual Slavery

I imagine a woman, wearing a skirt, who voluntary goes to a secret place. There, she is made to wear a leather slip with a dildo inside, that is closed with little padlocks. She is then given an address somewhere in town of a man unknown to her who holds the keys. To get free, she must go there by public transport, ring at the mans door, enter his place and please him in all ways he fancies until he decides to release and fuck her. Then, she leaves.