When you're an international superstar — when you're Julia Roberts or Tom Cruise, for example — it can be difficult for audiences to accept you in challenging roles, difficult for them to dissociate the persona from the performance. Lately this phenomenon also has been true of Angelina Jolie, with her well-documented adventures in adoption and globe-trotting with Brad Pitt.

But in "A Mighty Heart" as Mariane Pearl, the wife of slain Wall Street Journal reporter Daniel Pearl, Jolie reminds us that she really can act.

Director Michael Winterbottom ("24 Hour Party People," "Welcome to Sarajevo") wisely applies his trademark documentary-style approach, making us feel the building tension and dread as a multicultural coalition of investigators and journalists drops everything to track down Pearl's kidnappers.

Like the stylistically and thematically similar "United 93," this is a film that clearly needed no dramatic embellishment. And like "United 93," we know the devastating ending from the moment we walk in, yet may find ourselves silently, futilely hoping that things will turn out otherwise. Daniel Pearl was kidnapped and beheaded by Islamic militants because he was Jewish, and the killing was videotaped. Thankfully, though, we don't have to see it.

But being aware of his outcome makes each early moment sadly meaningful — the image of Danny (Dan Futterman) pulling away in a taxi for his fateful meeting while researching shoe bomber Richard Reid, a casual mention that he might be late for dinner, a perfunctory "I love you" on the cell phone before saying goodbye.

Once Danny fails to return to the home where they're staying in Karachi, Pakistan, on the night of Jan. 23, 2002, Mariane — herself a journalist for French radio — puts her skills to use trying to determine what happened to him. She is six months pregnant with their first child, a son Danny wanted to name Adam, but she moves quickly and efficiently. At her side from the start is his longtime friend and colleague, Asra Nomani (Archie Panjabi), but as the hours tick away and the situation grows more grim, their circle expands to include investigators, editors and ambassadors.

Leading the investigation is the head of Pakistan's counterterrorism unit, a man known as Captain (Irrfan Khan, with tremendous presence) who turns out to be more caring and sympathetic than he initially appears. He orders his men to scatter through Karachi's crowded streets, dark alleys and hidden back rooms, rounding up the usual suspects.

This, by necessity, takes us away from Jolie. We truly miss her presence, and when she's gone, "A Mighty Heart" can get a bit draggy. For a big chunk in the middle it feels like a standard crime drama — though it's a strikingly crafted and stirring one.