If you ever wanted to see The Mummy’s Evie Carnahan deck Peter Pettigrew for his Dark Lord-loving ways, finally there’s a movie for you… Well, kind of. That’s one very abstract way of looking at gripping courtroom drama Denial, starring Rachel Weisz and Timothy Spall.

More seriously, this real-life legal tale is set long before punching Nazis became a contentious issue. Instead, back in the late 90s, holders of conflicting opinions were forced to duke it out figuratively in front of a judge. That’s what happens to American professor Deborah Lipstadt (Weisz) when she calls British historian and known Hitler supporter, David Irving (Spall), a Holocaust Denialist. He turns around and sues her for libel in the UK, insisting her accusations have damaged his professional reputation.

Just as Lipstadt had to bear the burden under English law of providing proof for her claims, Denial’s filmmakers have the challenge of creating suspense out of something that on paper looks like it has a foregone conclusion. The trial is acknowledged in the movie as a David and Goliath battle, with racist, delusional Irving choosing to represent himself in court, while Lipstadt is flanked by her ace legal team and funded by multiple high profile donors. Surely the odds of victory are in Lipstadt’s favour in those circumstances? The audience can just relax, confident that the good guys will win, right?

Denial repeatedly makes the point that things weren’t actually so cut and dried. This said, the movie generates tension in other ways. Thanks to her spunky yet sensitive performance, the audience sides quickly with Weisz’s character. You share in her aggravation when her lawyers construct a defence plan without her input. You feel distrust when this same team behaves with apparent indifference and disrespect. And you get very angry when Lipstadt and Holocaust survivors are denied opportunities to speak in court.

As a viewer, your frustration levels continually rise. You crave the expected cathartic scenes you’d receive in a glossy John Grisham adaptation, for example. But what Denial does masterfully is remind that there are different forms of denial. And we’re not talking about the river in Egypt. Ba-dum-tss. Denial makes the point that what we want – what feels good – is not always for the best. The film becomes an effective, highly topical lesson in how to most effectively handle conflicting, or trollish, opinion. Spoiler: Don’t expect it to be easy!

Now Denial isn’t perfect. The film is quite heavy-handed with its messages. Characters routinely drop them in conversation, and there is one scene that could’ve contained a vintage Windows start-up sound it’s so blatant in outlining the movie’s themes.

For the most part you’re content to excuse these moments though, because the acting is universally outstanding. Spall brings an avuncular normality to Irving, in a chilling reflection of his “thought leader” type in reality. Sherlock and Spectre’s Andrew Scott is also memorable as hard-to-read solicitor Anthony Julius. However, it’s Tom Wilkinson who steals the show as a smoking, drinking, hides-sandwiches-in-the-cupboard barrister, whose quirkiness masks supreme professionalism and a rock-solid ethical core.

Denial may not be the most subtle movie, but you end it with the rare feeling that you’ve learned something – about history, about British law, but also about effective conduct in a heated viewpoint war.