After fulfilling his military service, Juan Pedro returns to Daroca, his small town. He meets Carmela, an attractive gypsy arrived at the town a year ago. Despite the rumors and prejudices, the couple decides to marry.
One of the staff girls at The Golden Mousetrap, a city nightclub, has been stabbed and is barely alive; a doctor is examining her in a dressing room. Inspector Simón leads the investigation supported by the night shift inspector Arévalo. The club management asks that nobody leave the place, since everyone there must cooperate with the police and being interrogated.
