Eva (Najwa Nimri) has just returned to work after having given birth to her second child. She cannot juggle the children, her husband Iñaki (Tristán Ulloa) and her job obligations. Carmen (Nuria González) is the most experienced of the three detectives, but her marriage is about to break down. Inés (María Vázquez) has just received her great breakthrough: she has to investigate the theft of goods from the multinational headquarters' warehouse by two employes, Manuel (Diego Martín) and another one. Valbuena (Fernando Cayo) is especially happy about the last job: it will mean high-level contacts and 30,000 euros in charges.
The first case we see concerns a married woman (Mabel Rivera), who asks the detectives to follow her husband. As she had thought, her husband was having an affair with an elegant woman, and they go to the restaurant where he had proposed to his wife, many years ago. Sergio (Antonio de la Torre)'s marriage is tumbling down, and Carmen is the one to videotape everything.
Inés reports that there are no reasons to blame Manuel and his workmate for the thefts - she even implies that it has never been any theft. When she gives her report, the employer wants Inés to find that Manuel is doing something illegal. The multinational wants to outsource the same workers they have under contract now, in practice paying them much less with no social benefits, and Manuel is the most representative Union worker. Valbuena is over the moon, as this would mean a new contract with higher wages and the detective agency taking charge of even a bigger problem. Inés and Manuel start falling in love. Manuel tries to convince all the workers in the company to go to the same day to the court and state the attempt to go against their rights, defacto overflowing the judicial system and forcing the company to discuss matters with the union.
Eva investigates her own husband; she thinks he's got a lover. Instead, she finds out that he has another son in Salamanca. When she confronts him, he says that he found out only two months ago, and that he was only waiting for the right moment to say. Eva cannot accept this, but Iñaki tells himself to their children, who accept the situation quite well and are even eager to welcome their new brother to the family. Eva stubbornly refuses to accept the situation, which puts a further strain in her relationship. Iñaki doesn't want to get separate or divorced, as he doesn't want to be an absent father. Eva also investiages the teenage love of an elderly man. He had never explained that girl why he left her. Eva finds that girl, now a widow in a small town in Zamora. The elderly man wants Eva to talk to that woman first, because he's too shy and too afraid of rejection.
Inés has also found something which Manuel is not doing right: he admits to her that he finishes up some taks in ten minutes, but that officially it takes him two hours. During that free time, he goes to the cinema to watch first-session films. Inés has found out what she was supposedly looking for, but as she agrees with Manuel's opinions, she shuts about it. There comes a moment that the executives learn of Manuel's meetings, and they call Valbuena, demanding the report. Valbuena is really angry with Inés: she has supported one side - the non-paying side, - she has shut up aboout the matter, etc. He also tells Inés to stop bringing her children to the agency, to charge the elderly man and dismiss him as Valbuena doesn't want to see him ever again. Carmen wonders if Inés should be working in the business, as she's taken sides. Valbuena is so angry with Inés that she won't be able to work as a detective again.
Manuel tells Inés that the company is suddenly open to discuss matters with the union. Inés gives him a copy of the images recorded with her hidden camera, telling him that he will understand everything when he watches the cd's. Right afterwards, Inés leaves.
The film ends with Eva, sadly following Iñaki once again.