Religion, morality and the law play a large role in “The Children Act,” a very exacting, almost clinical British courtroom drama.

But it’s in the interpersonal relationships of the main characters where the film shines in spite of the otherwise stuffy, cold narrative.

A collaboration between a group of producers including BBC Films and indie-heavyweight A24, “The Children Act” takes audiences on the other side of the courtroom as Mrs. Justice Fiona Maye takes on a heavy workload deciding complicated family court cases at the expense of her strained marriage.

A decidedly urgent and complex case involving a 17-year-old leukemia patient refusing blood transfusions on religious grounds proves as life-altering for the judge as the patient.

Such a cold, calculated film wouldn’t work without the electric and captivating performance from Emma Thompson as Fiona, often called “My Lady” as a sign of respect, disdain or admiration by various characters throughout the 100-minute running time.

As one character observes, viewers can easily see Fiona thinking as Thompson grinds the gears of her brain in a subtle, yet marked way.

Each decision is swift and precise, yet the downward spirals of self control failing to compromise with emotion weighs on Thompson’s somber gaze.

So much of the screenplay, penned by “Atonement” author Ian McEwen based on his 2014 novel of the same name, balances on the notion of choice and the ramifications therein.

Thompson’s performance perfectly encapsulates this notion as Fiona’s rational judgment gives way to complex moral ambiguity.

As much as viewers are to emphasize with Thompson’s rigid and faltering Fiona, Stanley Tucci draws audiences in with a blunt, matter-of-fact affectation paired with natural charm as her husband Jack.

In limited scenes, Tucci is able to generate enough exasperation to propel Jack towards ending his marriage, yet in a manner that seems casually reasonable.

Moments between Thompson and Tucci are so wonderfully fleeting that an entire two-hour feature could be devoted to the Maye’s marriage and viewers would be raptured. The subtle nuances in how Tucci and Thompson speak (and don’t speak) to each other make for terrific bursts of emotion in an otherwise languid screenplay.

“Dunkirk” star Fionn Whitehall is impressive in a challenging role as the patient of Fiona’s case, though difficulties present themselves in the final act of the film due largely to McEwen’s plot.

While there’s a sobering coldness to the entire screenplay, occasionally these moments of succinct dialogue find the mark brilliantly. Only in a dry British film can a character outright admit “I think I’m going to have an affair” to his wife with equal parts humor and dramatic tension.

Director Richard Eyre, who thrived on social tension with “Notes on a Scandal,” takes an observational, protracted tone with his filmmaking here. Shots linger longer than they probably should and often preclude tension by setting the camera a bit too far away from the actors.

The result is a mixed bag with Thompson and Tucci lifting up the entire project, though the film likely won’t have enough critical or commercial appeal to garner award season recognition.

With the prevalence of big studio films in theaters, solid adult dramas like “The Children Act” have been pushed to smaller screens.

Cobbled together on a relatively limited budget, there isn’t much of a place for “The Children Act” theatrically, opening this past weekend on just three screens nationwide. However, a partnership with DirecTV has pushed “The Children Act” to a much wider audience base, where it is available for rent or purchase on most streaming services.

Strong performances from leads Thompson and Tucci with crisp, impactful dialogue make “The Children Act” a feature film worth renting for a night at home.