In the first act of Taken At Midnight, Irmgard Litten (Penelope Wilton) looks ahead to a time when “all memory is forgotten and only history remains”. On Holocaust Memorial Day, and the 70th anniversary of the liberation of Auschwitz, many have reflected on the fact that survivors of the Holocaust will soon no longer be with us – the memories of these events may be lost forever. Perhaps theatre and other arts must shoulder the responsibility of preserving their voices and experiences.

Mark Hayhurst does just that in his new play, which premiered at the Chichester Festival Theatre last year. Focusing on the fate of lawyer Hans Litten – who dared to subpoena and cross-examine Hitler in a 1931 trial – and his mother’s tireless fight for his freedom, the work also looks at the wider politics of Germany in the 1930s, the relationship between mother and son, and the resilience of human nature.

Robert Jones’s design, which is starkly juxtaposed with the grandeur of the auditorium, splits the stage in two: downstage we follow Frau Litten’s indefatigable attempts to secure her son’s release, while upstage we witness him in so-called ‘protective custody’. Here, in spite of the play’s themes, there is plenty of humour generated by the fractious comradeship of cellmates Hans (Martin Hutson), Carl von Ossietzky (Mike Grady) and Erich Mühsam (Pip Donaghy). Their bantering and bickering is contrasted harshly with scenes of their interrogation and torture, suddenly sweeping us into the horrors of the regime that cannot be omitted any longer.

The cast is a strong ensemble, although I found John Light’s performance as Gestapo officer Dr Conrad rather hammy at times; it’s one of the details of the piece that makes it feel like a much older work than it is. Amongst the blustering of officers and politicians, and the fiery energy of the political prisoners, Penelope Wilton’s Irmgard is a reservoir of steeliness and endless patience. Her son’s cause becomes the essence of her life, and she spends the rest of her time reflecting on the changing nature of her country and wandering the streets, “looking for irony in people’s faces”. Yet it is also a fantastically nuanced depiction of this incredible character, as Wilton imbues the dialogue with dry humour, rage, desperation, heartbreak and bafflement – sometimes all at once. Her central performance transforms the play from an interesting historical piece into an absorbing drama of humanity, as the huge waves of political and military change are focused into a single mother-son relationship.

Act Two in particular is gripping, as the play moves towards its inevitably tragic conclusion; yet there is strength in the ending, too. Litten’s physical deterioration is shocking, but more so is the fact that he retains his concentration camp uniform for his flashback court scenes. As is fitting, the final declaration of rebellion comes not from any of the prisoners, but from the mother who questioned and risked so much for her son. A fascinating and powerful piece of theatre that already feels like a classic.

Taken At Midnight is playing at Theatre Royal Haymarket until 14 March. For more information and tickets, see the Theatre Royal Haymarket website.