NEW YORK (OSV News) – The BBC's screen version of Agatha Christie's 1944 novel "Towards Zero" is now available for streaming on BritBox. Though the book was a personal favorite of Christie's, this adaptation -- made up of three roughly hour-long episodes -- is a loose one that uses its source material merely as a template for a significantly altered story.

The original plot, for instance, features the fifth and final appearance of Christie's sleuth Superintendent Battle. In this retelling, however, Battle is nowhere to be found. Instead, the investigation is left to the superintendent's nephew, Inspector Leach, played to brooding perfection by Matthew Rhys ("The Americans").

Screenwriter Rachel Bennette delineates Inspector Leach as a weary figure, haunted by the lives lost under his command in World War I. The story picks up in 1936 with incidents that set the stage for a case that eventually comes to weigh on Leach's already despondent spirit.

At the center of the drama lies bedridden matriarch Camilla, Lady Tressilian (Angelica Huston). Wealthy and widowed, imperious Camilla presides over her family at their Gull's Point estate.

Gathering around her for an extended summer visit is a group of potential heirs, all of whom hope to be mentioned in the will Camilla is currently revising with her lawyer, Mr. Treves (Clarke Peters).

Viewing her guests with suspicion, Camilla invites Mr. Treves to stay with her for as long as they do. She's hoping his gravitas will add weight to her own heavy-handed management of the younger set. Labeling them "a brood of vipers" is just one in a series of put-downs she delivers with the force of so many dagger stabs as she keeps her cadre of hangers-on in their place.

For his part, Mr. Treves is less cutting -- and, perhaps wiser -- than his hostess. He also provides viewers with an explanation for the show's title. "I like a good detective story," he announces at an elegant dinner with the family. "But, you know, they begin in the wrong place.

"They begin with the murder," he continues. "No, no. The murder is the end. The story begins long before, years before, when the murder is seeded, the point zero, if you will."

The plot begins to thicken with the introduction of a love triangle. Camilla's nephew, Neville Strange (Oliver Jackson-Cohen), arrives at Gull's Point with his new spouse, Kay (Mimi Keene), in tow. But Neville, it turns out, has also invited his ex-wife, Audrey (Ella Lily Hyland), pitting the two women in a competition for his affections.

Though unrelated, Neville and Audrey both grew up at Gull's Point. They're referred to as childhood sweethearts, and Audrey describes their volatile relationship as "fire meets oxygen."

The couple's highly publicized divorce trial, centering on Neville's infidelity, makes the program's opening sequences seeth with confrontation. Their subsequent decision to reconcile as friends, accordingly, baffles the entire family -- especially Kay, who's determined not to be pushed aside for the woman she's just succeeded in replacing.

Other doubtful characters are introduced into the mix. They include Neville's newly acquired valet, who insinuates himself into the Gull's Point household so deliberately that his actions hint at ulterior motives.

Similarly, Camilla’s estranged nephew, Thomas Royde (Jack Farthing), returns from working in what was then the British colony of Malaya with no explanation for his mysterious, self-imposed exile. As for Camilla's hired companion, Mary Aldin (Anjana Vasan), she seems to be willing to gamble her security for a chance to escape the stultifying confines of her situation.

A coastal hotel known as a venue for illicit pleasure sits in view of the family's manse and seems to symbolize these characters' shared inclination to indulge in high-risk behavior. This is especially true for Kay, despite her insistence that her relationship with Neville has been transformed from the sultry affair that ruined his marriage to true love.

In short, hidden motivations abound, even among those who appear to be above suspicion. So, once two murders are committed, Leach will have to abandon his existential brooding, at least temporarily, and bring all his skills to bear to untangle the circumstances and identify where the real guilt lies.

Brief but explicit sexual content makes "Towards Zero" appropriate for grown-ups only.

Discerning adult viewers will likely observe that Christie's tale could have been made into a concise feature film and instead tends to drag over the course of three hours. Still, there's enough intrigue on offer to hold audience attention and enough character development to lend weight to the whodunit's outcome.- - -Garan Santicola is a guest reviewer for OSV News.