NEW YORK (CNS) -- "I want to know who I am," Matilda Gray (Lydia Wilson), the protagonist of the supernatural thriller "Requiem" says. By the time they finish the six-episode miniseries, which began streaming on Netflix March 23, viewers will likely identify this aspiration as an example of the saying "Be careful what you wish for."

Jointly produced with the BBC, where the series originally aired, "Requiem" opens in contemporary London. An accomplished cellist, 20-something Matilda is a rising star in Britain's classical music world, with billboards throughout the city celebrating her virtuosity.

On the verge of a larger breakthrough, which will take her to New York, Matilda is reluctant to tell her mom, Janice (Joanna Scanlan), about her plans. What she doesn't realize is that dark, troubling, ultimately fatal forces from the past have asserted themselves anew in Janice's life.

Following her mother's brutally sudden demise, Matilda discovers that Janice was obsessed with the two-decades-long missing-child case of 4-year-old Welsh girl Carys Howell (Emmie Thompson).

At first, Matilda can't understand why her Manchester-bred mum would have had any interest in the fate of a child in far-off Wales. But she eventually intuits that unraveling the Howell riddle will help her determine what happened to Janice herself.

Gray convinces her best friend and accompanist, pianist Hal Fine (Joel Fry), to travel with her to Carys' hometown, the fictitious countryside village of Penllynith, to further explore the mystery. Their arrival there coincides with the burial of Ewan Dean (Nick Hobbs), a suicide whose self-destruction may have been impelled by the same malignant influences that brought on Janice's death.

Ewan's grandnephew and heir, Nick Dean (James Frecheville), invites the newcomers to stay with him at the family manor where, in keeping with genre conventions, terrifyingly eerie things begin to happen. As with any gothic drama, viewers will need to suspend their disbelief, especially since any sensible real-life person would, of course, flee the Dean estate at the earliest opportunity.

In addition to the intensely dark -- indeed Satanic -- doings that unfold in "Requiem," the series is marked by violence, some of it portrayed in an unnecessarily gruesome manner, strong sexual content, a narcotics theme and vulgar talk. Even adults, accordingly, should take stock before choosing to watch.

More and more convinced that an understanding of Carys' fate will not only shed light on what befell Janice but on her own identity as well, Matilda presses the girl's remarried mom, Rose Morgan (Claire Rushbrook), for answers -- with nearly tragic consequences. Seeing this excessive pressure, Hal rebukes Matilda. "People," he says, "have been hurt by this, by you."

In her quest, Matilda also begins to discover that the good Christian folk of Penllynith are far from what they seem. The supporting cast -- Tara Fitzgerald as antiques dealer Sylvia Walsh, Pippa Haywood as psychologist Verity Satlow and Brendan Coyle as retired detective Stephen Kendrick -- successfully conveys the veneer of reasonableness and seductive solicitude overlying the sinister truth.

("Downton Abbey" fans will be especially glad to reconnect with Coyle, who memorably played the enigmatic Mr. Bates on that beloved series.)

"Requiem" maintains a sober tone and manages to avoid sliding into campiness thanks in large part to the commitment of its players. They help the audience to take the program's starkly weird world seriously.

Some viewers ready for a resolution may become frustrated, however, as "Requiem" tantalizingly dispenses its clues in little dollops. Moments intended to inspire terror, moreover, become so repetitive that they tend to distance the audience, inuring it to fear. Still, adults with a taste for the macabre -- and a tolerance for gritty material -- may want to give the series a try.

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Byrd is a guest reviewer for Catholic News Service.