El mercurio, el azufre y la sal

In the lake of the Casa de Campo Park in Madrid, the police find he dead body of Norberto Ruiz, a bookseller who dealt in old books. Alina, his daughter, is a young painter who lives alone in the city. As a result of the death of her father, who owned an exceptional book on the subject of alchemy, she gets involved in a series of strange events.
On failing to discover the book, the murderers try to pressure her. However, she has no idea what they are looking for; in fact, she and her father had grown distant ever since he decided to get married for a second time to a woman who was much younger than him.
Alina¿s investiations, helped by Yola (a 17-year old neighbour with she gets on well), put her in contact with two of her father¿s friends, who shared his passion for the art of alchemy. Moreover, she also has the support of her boyfriend Fran, who works in restoring old books. The two women follow different clues until they discover that the book on alchemy seems to be the motive behind the crime. In the end and to their great surprise, they discover the guilty party...