Mirren, Mirren, Mirren. The performance of Dame Helen—erstwhile queen, fabulously sexy senior—is the most talked-about element in The Last Station, Michael Hoffman’s dramatization of the final year of Leo Tolstoy’s life in which the Russian writer and his wife quarrelled over his invented religion and the cultlike followers it inspired. Christopher Plummer, who plays Tolstoy, has matched his co-star with an Oscar nomination. If only the rest of the film were worthy of the box-office attention it’s about to receive.

Showboating is best enjoyed when what surrounds it is understated. But whenever The Last Station isn’t rushing through story lines, it’s intolerably overwrought. The film, which Hoffman adapted from a Jay Parini novel, takes place in 1910 on a commune where Tolstoy spreads his message about peace, vegetarianism, celibacy, and the rejection of private property. He’s surrounded, according to introductory text, by those who regard him as “a living saint.” Among the believers are Vladimir Chertkov (Paul Giamatti), his partner and confidant; Valentin Bulgajov (James McAvoy), the slavish minion Chertkov dispatches to the commune as a spy and documentarian; Sasha (Anne-Marie Duff), Tolstoy’s daughter; and Masha (Kerry Condon), who admires the writer but modifies his preaching to meet her womanly needs, which she hopes the virginal Valentin will help satisfy.

Masha isn’t the only female of Tolstoy’s circle who refuses to check her sexuality. Sofya (Mirren), his wife of nearly five decades, is lusty and feisty, forever trying to entice Leo to their bed by reminding him of their early passion (“I’m still your little chicken…and you’re still my big cock!”). But she also is desperate for any intimacy with her husband, particularly because she rightfully suspects that Chertkov is persuading the ailing Tolstoy to change his will, relinquishing his work to the public domain and leaving their family with nothing. And so she spies, cajoles, and berates—not always with dignity—until everyone’s fed up with her theatrics. “You don’t need a husband, you need a Greek chorus!” Tolstoy admonishes in one of the film’s sharpest lines.

When Mirren and Plummer are together, whether thundering or giddy, The Last Station lights up. The bitterness of their characters’ arguments reflects the intense emotion all long-term couples are capable of unleashing, while their few moments of tenderness feel easy and natural. But Mirren’s Sofya steals nearly every scene thanks to her “me versus the world” attitude: She likes sex and material things and her husband as a human being. The others, though, “think he’s Christ,” and she can stomach only so much foolishness before shouting her mind.

It helps to know a bit about Tolstoy’s late spiritual awakening going into the film, of course—otherwise, the relentless ill will toward Sofya will seem puzzling. Also speedily unveiled is the romance between Valentin and Masha. He shows up at the commune, she shows up in his room, and suddenly they’re in love. Masha, at least, retains some depth of character (helped in no small part by Condon’s beguiling charm). McAvoy, though—well, his character sneezes when he gets nervous, a quirk that one guesses is supposed to add humor to all the drama. It distracts from what should be an integral character, a diplomatic go-between torn between his loyalty to the Tolstoyan movement and the sympathy he feels for Sofya. As it stands, Valentin seems little more than a what-does-she-see-in-him? pretty face. Worse, too many scenes are slathered with a treacly, self-important score. What’s most important—or, rather, most interesting—here is Leo and Sofya, though, and of that plot line there isn’t nearly enough.