To escape the heat of an August day in Madrid, Maite Zubiaurre ducked into an antique shop and there among world globes and old maps, she discovered a peculiar photo album. Tucked away among formal photos of King Alphonso XIII and Queen Isabel II was a whole collection of images of naked women and men. And, unlike the King, these women and men were not just posing. Rather they were engaged in a variety of unnatural sex acts, acts clearly at odds with...