Arsene Lupin (1978)

In a loop based on the historical example, Arsene Lupin is on the prowl, not only for jewels but also for the beautiful baroness (Brigitte Lahaie). At night the masked man climbs up to her balcony and gets involved in an extended orgy.
When activities calm down, Arsene Lupin takes his opportunity and takes on the baroness, before he vanishes back into the night.