Ironically, The Critic needed a little less beauty and a little more beast.

There’s a simmering quality to The Critic that never quite comes to a boil as Ian McKellen and Gemma Arterton lead an intriguing ensemble in a tale of blackmail, murder and betrayal that can’t hide the scars of reshoots and a reconfigured ending. Loosely based on Anthony Quinn’s novel Curtain Call, The Critic jettisons the source material’s murder-mystery narrative entirely, rearranging the characters into a web of manipulation, deceit and coercion centering on Ian McKellen’s veteran theatre critic Jimmy Erskine.

When the aged editor in chief of The Daily Chronicle dies, ownership of the newspaper falls to his son and new Lord Brooke (Mark Strong) who wastes little time in clearing house. In his cross-hairs are the “old guard”, veteran correspondents whose column inches are far exceeded by their expense accounts. Chief amongst them is legendary theatre critic Jimmy Erskine (McKellen), whose public vitriol and private peccadilloes make him something of a double-edged sword for The Chronicle. But when the paper cuts ties with him following his arrest for homosexuality, Erskine conceives of a plan involving stage actress Nina Land (Gemma Arterton) to get his job back.

It’s hard to go wrong when you have McKellen, who could probably deliver a captivating performance while the terms and conditions of a Disney Plus free trial agreement, but here every ounce of his Erskine’s venomous wit is deployed just to keep this otherwise aimless thriller steady. Erskine may be an old lion relishing the last vestiges of his waning power but his desperation to remain relevant in a rapidly changing world isn’t articulated well by a script which picks up and discards plot lines and historical details with the careless insouciance of someone browsing trinkets in an antique store to kill time. McKellen imbues Erskine with a complexity that’s captivating. He’s no one-note villain but a character you can’t help but be fascinated by, even if you’re rooting for his downfall. The problem is he’s playing to an empty theatre – there’s nobody to counterbalance him.

It’s interesting that the film has discarded so much from the source novel only to have to perform further self-surgery following early test-screenings because The Critic feels like a lost Agatha Christie tale only with the detective character (it feels like it would have been eminently suited to a certain Belgian) excised completely. So profound is the sense of absence you can almost perceive the missing character by the emptiness they leave.

The removal of an adversary for Erskine paradoxically doesn’t create more room for other characters to flourish. Quite the reverse, in fact. Arterton, Strong, Alfred Enoch and Ben Barnes – returning to the screen for his first movie role in nine years – all struggle to escape from McKellen’s gravitational pull. Arterton’s Nina especially feels like a character that should be more fleshed out but never quite manages to escape the eclipse of McKellen’s shadow. Arterton does well with what she’s given, but Nina’s transformation, while necessary to the story, feels underbaked. She starts strong, but her arc dissolves into predictability, as she at first supports and later grapples with Erskine’s manipulations.

The film swings between satirical critique of the power dynamics within the world of art criticism and the theatre, and a more personal drama of how far one will go to protect their legacy or achieve stardom, against a backdrop of the rise of fascism in the mid-1930s which it deigns to mention but leaves largely unexplored or commented on. There are moments where The Critic sparkles with biting humour and genuine tension, but just as often, it slips into a torpid melodrama through which McKellen’s Jimmy Erskine swims like a smugly solipsistic shark.

Director Anand Tucker captures the lavish, backstage glamour of the West End beautifully, giving us a sumptuous visual treat, but the script by Patrick Marber doesn’t always match the richness of its setting. It constantly feels like it’s pulling its punches in places, hesitant to fully commit to either the biting satire it promises or the thriller it teases. The central mystery doesn’t so much unravel as collapse into a hurried denouement and as sharp as it can be in the moment, The Critic is likely to fade from the memory as soon as the curtain finally falls.