C+

Meryl Streep gives another outstanding performance in “The Iron Lady,” doing a superb impersonation of Margaret Thatcher that captures the woman’s voice and mannerisms as perfectly as her take on Julia Child did, but goes far beyond mere external copy. Unfortunately it’s in the service of a script that lacks of the focus and intensity of the films it’s trying to emulate—most notably “The Queen” and “The King’s Speech.” It winds up seeming a truncated version of one of those multi-part docudrama mini-series that used to proliferate on the networks but have become an endangered species, except on cable.

Abi Morgan’s screenplay will undoubtedly come under criticism for drawing a portrait of Britain’s Conservative prime minister—who turned back decades of socialist Labour policy—that’s more critical than positive. But its basic problem isn’t ideological as much as structural. The genius of both “The Queen” and “The King’s Speech” is that they concentrated on particular episodes in their subjects’ lives, adding only the amount of background necessary for narrative context. By contrast “The Iron Lady” aims to cover the whole of Thatcher’s life story, and in doing so paints with too broad a brush. In trying to cover too much territory it meanders and flounders.

The entire film is constructed as a series of flashbacks depicted from the perspective of the aged, doddering ex-PM struggling to remain mentally clear even as she regularly converses with the spirit of her much-loved, deceased husband Denis (an exuberant Jim Broadbent). Their encounters take her back to recollections that run chronologically from her girlhood through the major stages of her political career, concluding with her removal from power as the result of a party coup.

The salient qualities that emerge, in the performances of both Streep and Alexandra Roach, who plays the younger Thatcher, are ambition, self-confidence and a congenital inability to suffer fools gladly. Though time is given over to Denis’ courtship of Margaret (her husband is played as a youth by Harry Lloyd) and their happy times together (symbolized by the Rodgers and Hammerstein song “Shall We Dance,” which periodically recurs), most of the footage is devoted to her unlikely political ascent and her tumultuous tenure as Britain’s first female PM. One can certainly read the picture as something of a feminist statement, but it’s doubtful that Thatcher would consider that a compliment.

In any event, the structure makes for a highly episodic biodrama in which only Margaret and Denis emerge as anything like rounded characters. There’s a one-damned-thing-after-another vibe to the film, with events rocketing across the screen like frenetic scenes in an overlong stage play. (Hey! It’s the Falklands War!) Figures like Edward Heath, Geoffrey Howe, Michael Heseltine and Michael Foot careen in Thatcher’s wake like so many puppets, one-note men cowering in her all-enveloping shadow. (Perhaps John Major is lurking even further in the background, but if so I didn’t notice.) The result is a picture that’s historically shallow, to say the least.

But if it doesn’t go very deep, the movie has an elegant surface, courtesy of production designer Simon Eliott, art directors Bill Crutcher and Nick Dent, set decorator Annie Gilhooly and costume designer Consolata Boyle. It’s a pity that their work in maintaining a persuasive—and attractive—period milieu is undercut by Phyllida Lloyd’s facile direction and Justine Wright’s rushed editing.

Of course, there’s always Streep, and—with the help of a coiffure that practically amounts to a special effect, as well as excellent makeup work—she cuts a predictably towering figure who dominates the film as completely as Thatcher did the affairs of English politics for more than a decade. But even a performance as formidable as Streep’s can’t overcome the unhappy fact that “The Iron Lady” is a sadly superficial treatment of the life and times of one of the most influential, and controversial, political figures of the late twentieth century.