It is pale, fearful and alert.

The tortured mother bird dips and dances to the demands of her angry cuckoo, her monstrous son Kevin. The film is a pungent depiction of maternal torment, but its weakness is that the torment never lets up.

The structure, which hints from the start at some terrible adolescent event for which the mother Eva is widely blamed, steals away suspense.

We're left in little doubt, early on, that a very bad thing happens, and it quickly becomes clear that Kevin is at the root of it. The question shifts from the "what" to the "why", revealed in passages of jumpy flashback: on this question, too, the answers are sparse.

Eva is mysteriously unhappy with her pregnancy.

When Kevin is born, he cries constantly, for no perceptible reason: his sole purpose appears to be to cause his mother misery.

As a small boy (Jasper Newell), he thwarts her at every turn, refusing to potty train or play ball, in any sense. Her sing-song voice fakes that of a naturally loving mother. Kevin smells the play-acting, and despises her for it. By the time he is an adolescent (Ezra Miller), sloe-eyed and ruby-lipped, his anger is seeking ever more flamboyant forms of expression.

Swinton is superb as a mother estranged from her child, whose frustration is so terrifying she can't permit herself to express it - except once, when she pushes Kevin over, fracturing his arm.

The film is often powerful, but it is one-dimensional and curiously unenjoyable.