Emma Thompson’s acting makes ‘The Children Act’ worth seeing

At the outset of The Children Act, a husband 20 years into a marriage and halfway into a tumbler of whiskey interrupts his wife's evening reading to politely suggest she permit him to have an affair.

It would be the decent thing to do, as he sees it. In pleasant tones, he notes that they've ceased physical contact, that he still loves her and wants to stay in their comfy marriage, and doesn't want to go sneaking about like some bounder. Surely she sees how sensible it all is.

Is this the most British moment ever committed to film?

Possibly, though the husband, named Jack and played by Stanley Tucci, is a Yank. Emma Thompson, though, is English enough for the both of them. As evinced in her reaction, a mixture of poise and astonishment, but mostly poise. She stares at Jack over her reading glasses, her expression suggesting that she may be losing her mind, but never her composure.

He politely makes his pitch; she politely tells him to pack a bag and leave.

Fiona (Thompson), we already know, is a cool customer — a High Court judge in the Family Division, known for her equanimity. This is established in early scenes, when she rules on the case of parents who wish their conjoined twins to remain attached, even if it threatens the lives of both. If this strikes you as Solomon-like, then the movie is having its intended effect. Based on a novel by Ian McEwan, The Children Act wanders into the tricky space created when what is moral and what is legal diverge, and law is made to suffice.

Secular and religious themes and references abound. Jack teaches philosophy and lectures his students on Greek and Roman philosophers whose ideas thrived before Christianity "closed the Western mind," as he puts it. Hearing this, we reconsider Jack's opening gambit – if fidelity isn't sacred, why bother?

Fiona struggles to come to grips with the disintegration of what she regarded as a happy marriage, and for the first time in her legal career, she is visibly flustered – a series of tartly amusing scenes show her being uncharacteristically abrupt with lawyers and witnesses (again, expertly played by Thompson).

It is in this state of flux that she takes the high-profile case of Jehovah's Witnesses, who refuse to permit the blood transfusion that will save the life of their 17-year-old cancer stricken son (Fionn Whitehead), too young to be his own advocate, though he insists he does not want the transfusion.

Fiona must decide whether to intervene, and listens to cogent arguments on both sides – legal boilerplate, I suppose, but in the hands of the cast, these scenes carry surprising emotional weight. The judge herself is moved and takes the unusual step of visiting the child in intensive care, establishing a deep connection that the boy is unwilling to forgo when the trial ends, leading to the movie's strange and not entirely plausible final third.

There is something a little tidy about the religious/secular ironies at play — a young man named Adam, for instance, in dialogue with an ultimate authority who adjudicates life and death. But that same dialogue narrows The Children Act to a two-character piece, one embodied by Thompson in top form, and she carries the movie home.