In 2013, a serious upheaval occurs in the Spanish judicial system due to the repeal of the Parot doctrine. Thanks to the repeal of this law, many criminals convicted of particularly serious crimes manage to be released early. The public reacts extremely negatively to this news. Among those dissatisfied with what is happening is Isabel Moro, who was raped by a dangerous psychopath in 1997. Now a police officer, she finds it a little easier to come to terms with the early release of Julian Lopez de Aro. Suddenly, an unknown avenger in a monkey suit appears, who begins to kill the amnestied criminals who have started committing new serious crimes. The investigation is entrusted to Inspector Isabel Moro, who must find the killer who has taken it upon himself to mete out vigilante justice to dangerous criminals.