It is 1881. In the town of Comillas, King Alfonso XII is visiting the Marchess of Comillas, a local noble, along with the Government and several businessmen, when an African servant called Tomasín brings several cups of liquor. While the men cheer, Tomasín shoots into the group, hitting the King while screaming about justice. The King's bodyguard shoots back, but it is too late: the king is gravely injured.
In the present, Salvador calls back to 1881, telling the President of the time
to prevent word of the events from spreading out of the place, after which he gives the patrol their new mission: they must protect the King (since his death would greatly change history) and find out what happened. And this suddenly becomes a bit more personal for Amelia when it turns out one of the businessmen present in the meeting is Pere Folch, Amelia's uncle. After a brief chat with Eusebi Güell, Amelia and Pacino walk with Pere along the gardens, where Amelia's alibi for working at the Ministry is revealed - a "noblewoman" (actually Irene) hired her to organize her deceased husband's library - and she implies she works for a newspaper, since Pacino is passing himself off as a journalist.
In the meantime, the king's doctor (a fellow agent of the Ministry) tries to cure the King, with Alonso acting as nurse, but there's a problem: the injuries are critical, and it is unlikely that the King will live beyond the day. The doctor tells everyone the King will survive, while the patrol investigates. Thanks to Sagasta's support, they get access to Tomasín's rooms, where they find something important: Tomasín was bought as a slave by the Marchess from Cuba and separated from his mother thirty years before - Tomasín found the documents and his attack was actually meant for the Marchess. The king on the edge of death, though, means that there's only one way out: changing history. Salvador immediately sends Amelia and Pacino to 1851 Cuba to rescue Tomasín's mother from slavery, while Alonso protects the king.
Irene and Ernesto discuss the troubles that have been affecting the Ministry of late, including Marta's escape and Lola's recruitment. Irene is obviously affected by the changes brought in, and is worried about the potential paradoxes caused by Lola's earlier recruitment (since this may mean she will not be recruited by past Salvador).
In 1851, after a brief visit to watch out for potential obstacles, Pacino and Amelia free Tomasín and his mother from slavery, along with all other men, while in 1881 two men attempt to kill the King while Alonso is on watch. However, just as one of them is going to stab the king with a syringe (shouting "¡Trágala, perro!") Amelia and Pacino bring the servant and his mother to the present, thus preventing the attack on the king and changing history the same way it happened back when Pacino discovered the existence of the time doors. However, this opens a new question: if the attackers were not from the Exterminating Angel (as the shout was used by liberals during Fernando VII's reign), who are they? Whoever did it, though, is likely to do it again - so Amelia and Pacino must return to 1881. But, as changing history meant that the patrol would not have come back in time, they have to act as if it is the first time they were there.
Back in 1881, Amelia and Pacino meet again with Pere, while Alonso investigates - finding the man that tried to kill the king now disguised as a servant. The patrol follows him when he leaves, but when Alonso attacks the would-be kingslayer, they are attacked by a group of men armed with handguns. And Pacino soon realizes who is leading this group: Amelia's uncle (which he realized when the man spoke in Spanish without any prompting, while the first time Pere didn't know about it).
This group is not the Exterminating Angel, though: they are the "Sons of Padilla" (named after the leaders of the Comuneros, Juan Padilla), a group that seeks to change history to make things more just for the Spanish people by any means, even if it is murder. Amelia's uncle offers her the chance to join the New Sons, but she rejects the offer, Pere leaves his niece to the men - and the patrol is soon forced on their knees to be executed. One of the men calls to Salvador, so they will witness the murder of the patrol, but suddenly one of the men turns on the others and kills them, before unmasking himself... or herself: it's Lola Mendieta!
While Lola unties the patrol, who thank her for her help, Salvador reveals to Ernesto, Irene and Angustias - who were there in the office watching the message - that he had asked Lola to investigate on certain events, and she found that Marta was involved in an attempt to get her father out of prison in the 1820s, along with other men that also were Ministry agents. Lola then offered to infiltrate the group in order to bring them down, which she did under strict orders not to reveal her mission. Her actions in the previous episode were part of her plan, and her loyalty to the Ministry is established.
But there is no time to lose: Lola knows that the Sons of Padilla have placed a bomb under the Marchess' palace, which will blow up while the King and the Government discuss the governance of the country. While Pacino prevents Amelia's uncle's escape (via a well-placed punch to the face), Alonso, Amelia and Lola go down to the basement. Alonso takes care of deactivating the bomb, while Amelia tells Lola she should not be there on account of her age, while Lola points out the same thing in regards to Amelia. Fortunately, Alonso, with the help of an explosives expert from the present, manages to stop the bomb before it explodes.
The threat stopped, Pacino arranges for the Marchess of Comillas to host Tomasín and his mother in his house, after which the patrol brings Amelia's uncle (whom Lola slaps him for calling her a traitor) to the present Ministry , where Salvador interrogates him. Amelia's uncle points out the good the Sons of Padilla could do - while also indicating that his time and the present are not so different - but nonetheless he is to be sent to the Ministry's prison.
Of course, this has serious consequences, not just for Spain's history, but for Amelia's personal history: Salvador tells Amelia that, as this event took place in 1881 (one year in her "past", since she now travels from 1882), much has changed. Her uncle's arrest led to the government expropiating all of Pere's business, in which Amelia's father was involved. Ruined, the man committed suicide several months later - exactly one year before her "present" day. Amelia breaks down crying, and tells Salvador she cannot continue working for the Ministry, as her mother needs her more than ever. Salvador expected it, and decides to help her and her family by giving her several serious tips on investment, so she can bring her family out of the ashes.
Leaving without saying goodbye (just like Julián did the year before), Amelia returns to her parents' (now her mother's) house, empty and bereft of the rich decorations that once adorned the place. Her mother appears, and both women hug, desolate and broken down.
Amelia takes some time to visit her father's tomb, but she then receives the visit of Alonso and Pacino, who are not about to let her go without saying goodbye - or, at least, a "see you later". The trio hugs between tears.
But the future holds still much danger. The Ministry is now under two threats (the Society of the Exterminating Angel and the Sons of Padilla), both opposed to the Ministry's mission and each other's. A Mêlée à Trois Civil War like nothing else Spain has seen is about to begin...
