A mental patient detained in a psychiatric hospital escapes from confinement and is dedicated to roam the outskirts of Madrid. His mind is no more disturbed rationale to kill. After murdering two girls on the banks of a river, go stringing a series of murders each more repulsive, spreading terror in the place. José and Antonio, two good friends, prepare a fun weekend at the country house that Joseph's family owns on the outskirts of the city. Taking this opportunity to invite two beautiful sisters, Anne and Laura, who accept the invitation. Ana, the eldest, works as a secretary, unhurried lives and loves Antonio. Laura on the other hand, has a shy and introverted character that has intensified after a recent failed love affair. Everything seems it will be a fun weekend for two couples.
John White, accounting for a large crime boss named Mancini is arrested and pressured by the prosecution to testify against Mancini before the grand jury, so it can be processed by one of his many crimes. Mafia boss knows that his book is a man of weak character who is likely to betray him, so he instructs one of his trusted men to do what it takes to make incriminating White not before the jury. Then decide to use such a Lan Moore, a sadistic sexual psychopath, to kidnap the wife of John White.
