Lona tries to learn more about the victim and how the body was discovered, and Elling learns that his wife couldn't have met with her intern that day, as according to a colleague, he was sick.

Arthur now questions Christa Hartmann more thoroughly. Marlis and Gerd find themselves in a severe conflict. Their different views on future and responsibility put their relationship to the test.

At the gruesome crime scene, the investigators find clues regarding the murder's motive, including something very disturbing about the victim.

Elling arrives at the crime scene. The criminal police investigators exchange initial observations, clues, and theories about how the crime unfolded.

The investigator Arthur gets one step closer to uncovering the secret behind the mysterious substances found in the baby carriage. Train driver Edith and Kurt, the cameraman, are also getting to know each other better.

The train is approaching Bamberg, causing the passengers to speak frankly with one another. Gerd is standing in the corridor and Marlis is sitting in the compartment. What will he decide?

For Chief Inspector Frank Elling, it's a relatively normal morning. But a strange case awaits him, involving a break-in, dead man, an old acquaintance, and a missing list.

The pressure on the train passengers increases as the train gets closer to East Berlin. Political views and personal desires and fears differ greatly, making it very difficult for couples to reach a decision.

The situation comes to a head with debates about idealism and disappointment, values of the East and the West, and freedom and control. As decisions are made, personal relationships begin to falter.

In the inter-zone train to East Berlin, people listen to the distressing radio reports. At the same time, we get insight into the lives of other people on this August 13, 1961 - the day when the Berlin Wall is erected and begins to separate its residents from the rest of the world.

Elke repairs the radio in the compartment and everyone hears the news: A wall is being built through Berlin and along the state border to seal off the Soviet zone.

The news of the Berlin Wall's construction continues to spread throughout the train. Arthur and Andi finally find what they have been looking for all this time.

As the train makes its way along, a reporter comes to interview Edith Salzmann, a locomotive driver. Through them, we get an impression of the roles and daily life of people in East Germany.

As the train continues its course towards Berlin, the band of musicians perform a song about yearning for freedom, which contrasts with the security checks of East Germans returning from the West.

August 13, 1961: A fateful message reaches the train bound for East Berlin: The construction of the Wall has begun. The passengers now have three and a half hours to decide—home or freedom?