Post-truth is the buzzword of the moment, so Denial, depicting holocaust denier David Irving’s mendacious lawsuit against a Jewish academic who dared to note he was a fantasist, is a timely story indeed. But Mick Jackson’s courtroom drama is about more than historic truth, it’s a forensic dissection of what informs so-called alternate facts. In this case, a toxic combination of anti-Semitism, Hitler worship and eye bulging intellectual vanity from a self-taught historian. This paradigm – prejudice, hate, ego, rationalisation, normalisation – seems to have widely adopted, both online and in the political sphere, so we watch this case study with interest.

Perhaps sensitive to the subject’s underlining importance, Jackson employs a matter-of-fact approach to the events under glass, resisting any conspicuous dramatic embellishments. It’s a necropolis for style. Consequently, the film has very little cinematic quality. What saves it is the weight of its wordy screenplay from playwright David Hare; a script that bares down on the legal questions with a barrister’s eye.

The filmmakers have chosen to reproduce the trial scenes verbatim, which lends them authenticity, but the setup is just as talkative. Essentially, this is a fine play about unmasking dishonesty and immorality, filmed. Could the story have been told with greater craft? Undoubtedly. But it’s hard to grumble when the words are so good and the performances uniformly excellent.

It’s a story that stays with you, particularly in those moments filmed at Auschwitz, with Tom Wilkinson’s Rumpole humbled by mountains of shoes and suitcases. The quiet power of the images cuts through, with a paralegal’s boyfriend later bemoaning the contemporary obsession with the event as a cautionary counterpoint. I was reminded of a holiday in the US many years ago when my travelling companion opted to visit the local aquarium rather than the Holocaust museum on the grounds that “we’ve learned the lessons, we should move on”. Denial is a reminder that such thinking is lazy and complacent, because the revisionists and sympathisers are always circling.

Rachel Weisz is a great fish of water as American defendant Deborah Lipstadt; a proxy for an audience incredulous at Irving’s lies and bemused by the intricacies of English law. Timothy Spall plays the racist historian as an odious, vainglorious sleaze, who matter-of-factly talks about women’s breasts while showboating to TV reporters, more perturbed at a thrown egg soiling his suit jacket than the accusation he teaches his child racist nursery rhymes. The strength of those performances, with great support from Andrew Scott as Lipstadt’s solicitor, makes Denial a powerful spectacle, despite its cinematic shortcomings.