It is 1940. Across the forests of France, two La Résistance members are running away from the SS. One of them is killed by gunshot, and the other trips. However, before the SS can kill the maqui, he tells them he has a secret he can reveal to Hitler: he knows how to travel through time.
Alonso, Amelia and Julián are getting used to their new job and the new times. Meanwhile, Lola Mendieta brings two men from 1940 to 2015. However, when one of the men falls ill and is taken to a hospital, the Ministry finds out about Spain's potentially joining World War II, as Adolf Hitler seems to be ready to accept all of Francisco Franco's demands.
Ernesto travels to 1940 Madrid, where Heinrich Himmler is staying as a guest of the Spanish government, preparing the details of Hitler's meeting with Franco, and bugs the phone in Himmler's room. Apart from a demonstration of Himmler's hypocrisy (deriding bullfighting as something monstrous, to which Salvador sarcastically mentions Auschwitz must have been a family friendly show), Himmler mentions in a conversation with Hitler that the Holy Grail is in the Montserrat Abbey
. However, it is obvious that what holds the Abbey is a time door.
The alarm is sounded out, and Alonso, Amelia and Julián are given the task to travel to the Abbey and destroy the time door before Himmler can take control of it, while Ernesto and Irene join the expedition for the meeting between Hitler and Franco in Hendaye, Irene as a nun and Ernesto as the translator between both leaders, with a secret mission: kill Hitler if it looks like Spain is going to enter the war.
The Power Trio arrives to Barcelona, where Amelia is shocked to see a painting of her family (which was being painted at the beginning of the episode), before they leave for the Abbey. In the meantime, the maqui sells Lola out to the Nazis, who forced her to lead Himmler to the time door. Alonso, Amelia and Julián end up captured, and Lola ends up telling the Nazis that she knows a place with not only one, but many time doors: the Ministry. The Nazis kill the maqui and send a squad to 2015, to take over the Ministry, catching them by surprise. Salvador, too, is captured, but not before he manages to warn the security service about the invasion.
While Alonso and Julián free themselves and warn the Ministry agents out of the Abbey, Ernesto fears the worst has happened and prepares to poison Hitler, who has received a call from Himmler, telling him that the time door is real. It is then that the Ministry's security service appears: a squad of the Flanders' Tercios, led by General Ambrogio Spinola (Ramón Langa, better known as Bruce Willis' Spanish VA), which kicks ass, killing most of the Nazis without taking losses. Nazi captain Schweinsteiger retains Salvador as a hostage, but Alonso and Julián have also taken Himmler prisoner. The captain gives up, and Himmler is forced, under the threat of killing his parents and prevent his birth, to tell Hitler it was all a dream. Hitler, furious, calls off the meeting and the agreement (dropping a Precision F-Strike).
While this is happening, Amelia has Lola at gunpoint, and the two women argue. Lola states that the Ministry's intended mission, to keep history as it is, is a mistake, as history has many horrible moments that should be prevented. Amelia points out her role in the attempted murder of El Empecinado, but Lola replies that her plan was to make Spain lose the Peninsular War, as victory brought Fernando VII back and, with him, absolutism. Amelia, clearly affected, can't bring herself to shoot Lola as she flees.
Before coming back to the present, Amelia visits Barcelona's graveyard, where she makes a horrifying discovery: her own tomb, stating she will die five years after her recruitment, leaving a husband and a daughter behind.
