Tully film review: Charlize Theron shines in this dark film

We meet the family days before Marlo is due to give birth to her third child.

When her sister-in-law tells her she is “blooming”, she mutters, “Such a blessing,” her sarcastic tone revealing the first fissure in a happy facade.

Soon other cracks begin to appear.

Their special needs son is about to be expelled from kindergarten, their daughter is starved of attention and Drew prefers blasting zombies on his games console to talking to his wife.

After their third baby arrives, these cracks start widening into deep ravines. This is Reitman and Cody’s third film after Juno and Young Adult and a late twist will probably make it their most divisive.

But there should be no arguments about Theron’s fierce performance.

The dark script puts Marlo’s frustrations on a very slow boil but it builds to a spectacular climax and the Oscar winner makes it almost impossible to look away.