In Clint Eastwood’s latest film “Changeling,” Christine Collins (Angelina Jolie) tells her son, “Never start a fight, but always finish it.” Though it’s no “Million Dollar Baby,” “Changeling” stays true to this charge, fighting to tell a story of justice and loss till the very end of an emotionally turbulent 140 minutes. Jolie’s impassioned performance at times veers into the melodramatic, but it’s the lifeblood of “Changeling” and more than makes up for underdeveloped characters and a structure that feels too self-aware.

As Collins, Jolie plays a single mother in 1920s Los Angeles who one day returns home to find her son missing. In an exhilarating, Oscar-worthy performance, she moves us to tears, frustration, and terror. “Changeling” moves beyond the heart-rending concept of a mother’s love for her son and soon evolves into a fight for justice and a mysterious case of missing children.

The intrigue is heightened by the addition of several unknowns—a psychiatric ward, an LAPD as callous and corrupt as it is lazy, and a mechanic just a tad touched in the head—but we are nonetheless treated to Jolie repetitively screaming with varying degrees of despair, outrage, and panic for her son. Were Jolie an actress of lesser talent, “Changeling” might not be more than a slideshow of extreme human emotions.

Nevertheless, close-ups of Jolie manage to make us feel what we ought to feel. In the glitter of her huge doe eyes we recognize the docility of a character who, at first, is neither radical nor rebel. When Carol Dexter (Amy Ryan), a prostitute imprisoned in the same mental asylum, tells Christine, “I had two abortions by back-alley doctors. I didn’t have a choice to fight for my kids...don’t stop,” we see the beginnings of determination working in the very way Jolie holds herself.

It’s a good thing Jolie’s performance is so solid, because she carries most of the weight of the film. The accompanying cast includes John Malkovich, who plays Gustav Briegleb, a Presbyterian reverend who has made it his life goal to expose the LAPD for the fraud it is, and Jeffery Donovan as the unscrupulous J.J. Jones, captain of the LAPD juvenile investigation unit. Despite their roots in a true story, both characters seem flat. Briegleb, with a single-mindedness that is more annoying than inspiring, pops up every once in a while to warn Christine of the LAPD’s next move, as though his only purpose is to inform the audience. Jones is far too much “the bad guy” to have any depth. Dexter’s character is refreshing, while Jason Butler Harner, who plays Gordon Northcott, the mechanic of questionable sanity, is convincing in his quiet leer and uneasy smile.

As is the danger with a film that draws from real life, “Changeling” follows the template of Collins’s true story far too literally. Some scenes that loyally adhere to actual events detract from the overall spirit of the movie. Though most of the film’s questions are answered two-thirds of the way through, it continues to roll with an impatience for finality and a self-conscious pace that the audience feels.

Eastwood, however, does know how to milk a climactic scene for all its worth. One scene in particular is tense to the point where it is almost unbearable to watch—and therefore all the more impossible to ignore. In a time where the public is not at its coziest with bureaucracy, Christine’s story and the ramifications of her actions strike a chord.

Eastwood is clearly a master storyteller, but “Changeling” does not have the same quality that some of his darker films, like “Mystic River,” can boast. In spite of all this, “Changeling,” unlike Eastwood’s other bleak dramas, revels in the capacity of the human spirit for strength and love—something that, as Christine says, “Gives me something I didn’t have before tonight—hope.”