Angelina Jolie makes a strong bid for an Oscar nomination with her tour de force portrayal of a crusading mother in Clint Eastwood’s harrowing drama.

Based on shocking true events from the Los Angeles police files, adapted for the screen by J Michael Straczynski, Changeling is a cautionary tale about the abuse of power and the extraordinary influence of one individual on a corrupt system.

Eastwood underscores Tom Stern’s flawless cinematography with his own mournful orchestrations to evoke the twilight years of the 1920s, an era of post-war prosperity when families could leave their doors open at night.

Against this impressively recreated canvas of restrictive fashions and vintage cars, single mother Christine Collins (Jolie) raises her nine-year-old son Walter (Gattlin Griffith) by working as a supervisor at the city’s telephone exchange.

One weekend, Christine is unexpectedly called into work and when she returns home, Walter has disappeared without trace.

After months of fearing the worst, Captain JJ Jones (Jeffrey Donovan) contacts the mother with incredible news: Walter has been found safe and well in a neighbouring state and is on his way home.

Overcome with joy, Christine races to the train station only to find the boy (Devon Conti) who claims to be Walter is an impostor.

With the press swarming and Captain Jones desperate for a happy ending, the mother is forced against her will to take in the child as if he were her son.

“He has nowhere else to go,” Jones whispers, using emotional blackmail as his last resort.

At first Christine agrees but she eventually buckles and threatens to expose the lie.

“Are you a derelict mother or are you nuts because where I sit those are the only options?” rages Jones, despatching her to the mental asylum until she signs a statement agreeing the returned boy is Walter.

Just as all hope seems lost, Presbyterian preacher Reverend Gustav Briegleb (John Malkovich) and his allies launch a campaign to release Christine and expose corruption in the LAPD.

Changeling unfolds without fuss or fanfare at the leisurely pace, which has become Eastwood’s style, cutting back and forth between Christine’s story and a parallel police investigation to apprehend suspected child serial killer, Gordon Northcott (Jason Butler Harner).

The two narrative strands collide in a brilliantly orchestrated interrogation room sequence, during which Northcott’s nephew (the mesmerising Eddie Alderson), reveals Walter’s fate.

Jolie is sensational as a woman on the verge of a nervous breakdown, who screams and shouts for justice, fearful she might not get the answers she craves.

We share her sense of outrage, shedding tears as the asylum’s insidious head doctor (Denis O’Hare) threatens to destroy Christine’s resolve with electro-shock therapy.

Donovan is equally compelling as a chauvinistic bully determined to restore his department’s tarnished reputation, complemented by a restrained turn from Malkovich as the man of God who warns Christine of what she is up against.