There’s a heartfelt impetus behind Amma Asante’s new film, a period drama set in Nazi Germany with an interracial theme at its heart. The film gives us elements of melodrama and also of epic – yet there is also something a little uncomfortable about it.

Asante’s original screenplay is inspired by the historical case of what were crudely called Rheinlandbastarde, mixed-race people in Nazi Germany who had been fathered by military personnel of African background in the Occupied Rhineland after the first world war. These people were not technically subject to the oppression suffered by Jews and yet had to be sterilised, or at any rate produce documentation to show that this procedure had been carried out. They inevitably endured endless racist harassment as well.

Amandla Stenberg plays Leyna, a young biracial woman whose mother, Kerstin (Abbie Cornish), had a relationship with a French-Senegalese soldier. Lutz (George MacKay) is a young Nazi officer who falls in love with her in 1944; they are separated by the war as the Reich collapses and Leyna is finally sent to a concentration camp where Lutz has inevitably been posted as a guard.

The romantic relationship with the “good Nazi” is a little too glib (quite as it was in the film version of Suite Française) and the camp scenes have a misjudged sheen of romanticism and come perilously close to the bad-taste border. But Stenberg’s performance is good and there is a shrewd contribution from Christopher Eccleston as Heinz, Lutz’s cynical and careworn dad.