What is the secret of the bone case which Sara bought at the market of Plaza Redonda in Valenza? Whatever the secret is, Sara and her twin sister Lola can’t sleep anymore: a mysterious plumed snake appears in their bedroom every night and wakes them up. Their investigation leads them to a strange professor…

Brother and sister, Lola and Alejando – who are students at the University of Saragozza – decide to go to San Sebastián to the International Film Festival. In the middle of all the famous actors, film premieres, Lola, who dreams of becoming a journalist, and her brother investigate the disappearance of the famous actress, Gloria Borja.