Various inmates accused of rape, murder and terrorism are released before their sentences are full. Hours later, one of them is murdered. Detectives Mora and Nieto take upon the case.
Isabel and Nieto investigate a new attack. Terrorist Basauri has been beaten up after being released. Rapist Haro takes advantage of his retrieved freedom to spy on Isabel's life.
The investigation of the murders takes a hit when the monkey masks become a trend during Carnival, since the murder wears one. Haro's antics begin affecting Isabel's life, whose emotional stability is a bout to be put to a terrible test.
Worried for Isabel's mental health, Nieto tries to get her out of the case to decrease her pressure. As the case gains attention on the media, the Ministry of the Interior calls for a tense meeting over the state of the investigation.
The murderer acts again, now upon an ex-jailed neo-nazi. This time, however, her loses the mask in the struggle. The ex-jailed begin manifesting in front of the station for protection, increasing the pressure on Isabel and Nieto.
The investigation of the case takes Nieto to the zoo, where someone has freed all the monkeys from their cages. Haro continues playing with Isabel's physique.
After the murderer acts out once again, Nieto continues with the investigation amid the Commissioner's reproaches. Haro arranges for an interview with Ana to wash his image in the media.
Despite the Parot case being handed over to another inspector, Nieto continues investigating on his own. Meanwhile, Isabel tries to adapt to life at a mental health center.
Thanks to Nieto's finding, the murderer's identity is finally exposed and the police makes it public to the media. Haro contacts Isabel to force her to come into an encounter with him.
