Chris Evans plays a stubbly blue-collar hunk who fixes boats for a living and has raised his niece (Mckenna Grace) on his own.

Now seven, she is a mathematical genius with a mind ‘rarer than radium’.

Evans wants her to have a normal childhood, unlike his hot-housed sister, another maths prodigy who killed herself when his niece was six months old.

However, this puts him at odds with his estranged, wealthy and snooty British mother (Lindsay Duncan). When she turns up on the scene, the stage is set for a mighty custody battle.

To Duncan, Evans’ easy-going care of Grace amounts to negligence, while he fears his niece will spend her childhood discussing non-trivial zeros with a bunch of old Russian guys if left in his mother’s charge.

But what outcome is best for the child?

In solving the question, this film is undeniably contrived and manipulative. However, the fine cast put things together with such charm and humour that you’ll be quite happy having your heartstrings gently tugged.