It is the year 1960. A young woman stands on the edge of a building's roof, clearly intending to jump. When the camera pans up, it turns out to be a young Irene Larra: at the time, she was a married woman that worked in the Ministry of Information, but between her closeted lesbianism in ultra-Catholic Francoist Spain and her work troubles (after discovering some unknown illegal dealings within her workplace) she has decided to put an end to it.
However, someone speaks to her: Armando Leiva. The man - obviously much healthier and younger than the one seen in the previous episode - convinces her not to jump, offering her a job in another place where she will have a much better life.
Jump to the present: Irene wakes up. It was all a dream, brought on by Leiva's death, which has deeply shaken her. Next to her wakes Nuria, Irene's wife. The two of them talk, and Irene suggests they spend some holiday time in Paris, before she leaves for her job.
The trio meets visibly affected Irene as they return from a mission to the times of King Philip V, and ask Angustias about it. Angustias reveals to them Leiva's story: he was a Carlist War hero who got recruited by the 20th Century Ministry and rose through the ranks, eventually becoming Operations Chief (the position Ernesto now occupies). However, in 2005, Leiva asked Salvador for permission to bring his son (who suffers from leukemia) to the present, so he can be treated, and also states that they should use their knowledge of modern medicine to save lives in the past. Salvador denies both requests, pointing out that changing the past is a very risky affair, and that using the time doors for personal gain is forbidden. This led to a faction of Ministry workers, led by Leiva, to go on strike to demand for changes in the Ministry, and later even attempt to take over, but someone betrayed them and Leiva ended imprisoned, while his son died.
Meanwhile, Salvador and Irene go to 1053, to witness Leiva's burial, during which they speak about the horrible condition Leiva was left in. Back in the present, Irene looks on a photo of happier times (one where she appears with Ernesto, Salvador and Leiva) and Julián, trying to console her, invites her to have some drinks. After Irene explains why she has no problem at sleeping with other women while in the past (since her affairs happen in times before she married Nuria, it technically does not count as infidelity), Irene asks Julián if he is still meeting with Maite in the past, and tells him to stop doing it, before it becomes too dangerous and he accidentally changes the past. Julián has sex with another girl he meets in the bar, but the following day he begins to check on the days he was working back in 2012 so he can spend time with Maite, unmolested. As he goes to the past, his beeper sounds, but he does not pay attention.
Salvador is summoning the team: someone has stolen Leiva's body. Alonso and Ernesto travel to 1053, to check if they can find anything, but there is no proof. Amelia, meanwhile, goes to Julián's house: she does not find him, but when she sees his agenda she realizes what he has done. Meanwhile, Irene is kept away from the mission due to her personal implication with Leiva.
It turns out that Leiva never died, but instead was planning on escaping: just after the burial, a group of his men revived him with a shot of adrenaline. Leiva then goes to the year 2005 - just before his Start of Darkness - and asks 2005!Angustias to let him into Salvador's office, which she does. Leiva leaves soon, but Angustias realizes something fishy is going on when 2005!Leiva appears, nonchalantly asking after Salvador. She then sends a fax to her future self, warning herself about what's going on, and Salvador calls 2005!Angustias, who tells him that Leiva has been checking on the 1844 files, a time in which the Ministry was nearly closed down - and the time from where Leiva comes from.
Salvador immediately deduces that Leiva is planning to go to that year, particularly the day when Isabel II
, then a young 14-year-old girl and Queen, along with her sister and the Queen Mother, visited the Ministry. Leiva's son being already dead, it is obvious he intends to cause harm to the Ministry in some way.
Leiva is a step ahead, though, and has already brought his men to 1844. These men place signal inhibitors in the 1844 Ministry, so they cannot communicate with past or future Ministries. Leiva meets with Emilio Redón, the Ministry Secretary of the time, to warn him that a group of Carlists intend to murder the Queen and her family, and that he has been ordered by Salvador to take over the Ministry's security. Unable to call Salvador to confirm this, Redón accepts the offer, and Leiva places the security around the gate to 2015.
Salvador decides to send Amelia, Alonso and Ernesto (replacing Julián) to 1844, so they can stop Leiva's plans. Irene, meanwhile, is warned by Amelia of what Julián is doing, and she goes to 2012. Amelia, Alonso and Ernesto are captured: Leiva shoots Alonso in the stomach and kills all of the security men in the 1844 Ministry, taking over the place and kidnapping both the Royal Family and Redón, before calling Salvador and telling him his plans: he intends to kill the Royal Family, so the Carlists can take over, and completely change Spain's history.
Irene, in 2012, finds Julián in his house, and tells him what is going on. Julián initially waves her off, unconcerned and somewhat fed up with working for the Ministry, but Irene convinces him to come back, telling him that Amelia and Alonso are in danger. Before he leaves, though, he tells Maite to make it like he has not spent the day with her, telling no one, not even himself.
Julián and Irene travel to the past, armed and armored, and manage to save their friends and the Royal Family. While Julián and Amelia stay in the past, taking care of Alonso, Ernesto and Irene go back to the present, where Leiva has gone as well: he is torturing Salvador to find out who betrayed him and his men. Salvador tells him how to find the information, and Leiva is surprised to learn it was Irene.
Irene arrives right on time to learn that Leiva has left... and has kidnapped Nuria. Given the comments Leiva makes, Irene realizes that he has taken Nuria to the same building where Leiva prevented Irene from killing herself, but in the present.
Irene reaches the roof and finds Nuria, her hands tied to a rope that Leiva is holding and standing in such a way that she will fall from the building if Leiva lets go. Leiva states aloud all the secrets Irene has kept from Nuria (the Ministry, her time-traveling, her origins), and Irene is unable to rebute them. Leiva helps Nuria return to a safe position, having fulfilled his objective of destroying Irene's life much like she destroyed his, and jumps over the edge, killing himself.
Back in the Ministry, Alonso has survived his injury, thanks to rapid healing and a blood transfusion from Amelia - something that makes him feel weirded out. The Queen Mother intends to close off the Ministry - never mind the problems this would cause - but Queen Isabel tells her mother off. To further convince the Queen to keep the Ministry open, Salvador asks Ernesto to show her the wonders of the future.
Ernesto ends up taking Isabel and her sister to watch a movie in 3D in the cinema.
Irene tells Julián some bad news: Nuria has decided to leave her. Now, the only thing she has is the Ministry, much like Julián.
