This gripping legal drama is based on a case we still don’t know the truth of — which might make it seem like a pointless exercise, were it not for the fact that it’s infectiously fascinated by greater questions than whether wealthy socialite Claus von Bülow (Jeremy Irons) really did attempt to kill wife Sunny (Glenn Close), who was left comatose by the mysterious event. After being convicted, Claus recruited for his appeal then-hotshot lawyer Alan Dershowitz (Ron Silver), now better known for personal allegations and his defense of men even more nefarious than Claus. Reversal follows the tricky legal argument-crafting process, embedding us with Dershowitz’s elite team as they meticulously comb through the prosecution’s theory to find the hairline crack they need to break the case open.

But why go to all this effort to exonerate an unlikeable and frustratingly enigmatic man like Claus, whom Dershowitz apparently doesn’t even believe himself? While we’re morbidly fascinated by unknowable cases like this, it’s the passion of the defense that’s really puzzling — something Reversal shrewdly gets as it wrestles with the ethical arguments for and against Dershowitz’s involvement, making for a pre-courtroom drama whose power extends beyond that of the particular case it documents.

As the morally ambiguous hinge on which Reversal turns, Irons’ role is the trickiest to get right, but he pulls it off with consummate flourish. His Oscar-winning performance as the drawling, emotionally aloof Claus is balanced on a fine knife edge: everything about this man overwhelmingly screams “guilty!”, but there’s an unflappable sense of righteousness about him that’s seemingly bolstered by the facts of the case. Though we’re all but ready to send him to the gallows in the beginning, Irons deftly maneuvers Claus into a frustrating yet fascinating grey area over the film’s runtime, revealing him as a deeply complex figure. Blending simmering menace with closet fragility, Irons’ extraordinarily modulated, masterful performance gives the film the moral conundrum it needs to work.