It was long said to have been the most significant decision of Angela Merkel’s 14 years as German chancellor. Now the political and social drama of the refugee crisis in 2015 has been turned into a feature film based on a bestselling book.

Merkel: The Driven charts the twists and turns surrounding the decree that allowed almost a million refugees into Germany.

The film culminates in her resolve, despite opposition from many of her political friends and foes, not to close Germany’s borders after thousands of refugees, mainly from Syria, boarded trains at Budapest’s Keleti station and headed for Germany, after the police who had been stopping them from leaving were withdrawn.

The film’s director, Stephan Wagner, said the film was as much a political thriller as it was “a portrait of Merkel, focusing on a turning point in her time in office”.

It is based on Robin Alexander’s 2017 bestseller The Driven Ones: Merkel and Refugee Policy, in which the long-time political correspondent for Die Welt offered a behind-the-scenes account of the 63 days of political intrigue and back-biting that changed modern Germany.

It shows Merkel sticking doggedly to the idea of a political solution before dividing opinion among both her opponents and party colleagues with her decision not to close Germany’s borders. She calls her stance as a “humanitarian imperative”, but the film portrays it in much more ambiguous terms, suggesting Merkel was reluctant to be seen as the “refugee chancellor”.

Imogen Kogge, who plays Merkel in the film, well-known to German viewers as police commissioner Johanna Herz in the popular series Polizeiruf 110, said the film threw light on the complexities of communication, “on how communication occurs on the highest level when there is quite simply a lack of solutions”.

She said that playing one of the most famous women in the world had not been straightforward: “That everyone inside and outside of Germany believes they know Merkel well did not make it particularly easy to approach the role. But once I was assured it was not about impersonating her, but in the first instance to find certain recognisable characteristics, I felt relatively free.”

The drama starts with Germany stuck in the middle of the Greek debt crisis, when Merkel’s finance minister, Wolfgang Schäuble, is pushing for a “Grexit”, the expulsion of Greece from the eurozone, against Merkel’s will. She is then abruptly informed that Hungary intends to build a border fence to stop the refugees from war-torn Syria entering the country and a whole new crisis starts to unfold.

It is shaped by Merkel’s attempts to push the issue away and put off any concrete decision-making, as well as the increasing divide between those Germans who want the country to welcome refugees and those who angrily reject the idea. The resulting tension continues to define German politics today.

The film was set for a German cinema release at the weekend but will now be shown by the state broadcaster ARD on 15 April due to the coronavirus crisis – which, unlike in 2015, did lead Merkel to close the borders.

“The events of 2015 continue to shape German politics very much to this day,” the producer, Alexander van Düllman, said. “As Germany prepares to bid farewell to Angela Merkel the refugee question still remains a very fragile one.”