Seven books, Seven sins

Andres, the police inspector of the Judicial Police of the COU of Madrid, was sent to Gerona shed light the first cime, impossible to forget. A month prior, the killer had chosen the traditional way to send his manuscript. A pair of shaky hands left over the counter of the Mail the package of four hundred printed pages. It was his first novel. And six more would follow, all of them rejected by the publishers, but the seventh would be his magnum opus.
Andres, a staunch smoker and working by his own rules; discovers Marta, a young hacker with a traumatic past that will help him decrypt the messages the murder leave behind with the blood of his victims. Andres and Marta are always two steps ahead of the Judicial Police of Gerona and the killer is always one step ahead of them. This unleashes a race against the cat and the mouse in an unforgettable thriller.
"Im not the first nor the last" the killer always writes. They must decode the message to find him and avoid a murder.