The third season of “Dalgliesh,” again features three two-part adaptations of P.D. James’ acclaimed murder mystery novels starring Scotland Yard Commander and poet Adam Dalgliesh.

This season Bertie Carvel not only reprises his super sleuth but, for the first time, steps behind the camera to direct.

“Cover Your Face,” an Agatha Christie-style whodunit from 1962, was the first of eventually 14 Dalgliesh novels James wrote.

In a baronial mansion, the patriarch lies dying in bed, plugged into machines. His wife, their two adult children and their partners are live-in residents when the young housemaid, a single mother of an 11-month-old infant, is murdered.

This AcornTV version updates the timeframe to 1979 and makes other significant changes as well.

“What I love about the story is that it’s focused on the family,” Carvel, 47, said in a phone interview from London. “And what a fascinating family they are! But it’s been reframed and is quite different from how it was originally presented in 1962. It’s always been a story about prejudice, to some extent, against this young woman who ends up dead.

“And — spoiler alert! — she’s dead essentially because of her social class. But they’ve widened that frame and asked, How can we tell a story more widely about prejudice?

“By making the Mehtas a British Indian family, they do something quite subtle but extremely profound: They hold that idea of prejudice up to the light in the context of 1979.

“And the harmonics of that are really interesting in light of what’s happening in contemporary Britain — and without hammering anything over the head. So I was thrilled to be chosen to direct that particular one.”

Would Carvel consider that Dalgliesh is P.D. James’ Sherlock Holmes?

“Well, I think that’s a neat formulation. What does he have in common with Holmes? I suppose his intellect.

“But his superpower seems to me is his emotional intelligence. Sometimes he is emotionally detached — or can seem emotionally detached. Reserved.

“Actually, I think he’s emotionally extremely porous and that’s what makes him both a good poet and a good detective. His ability to think with his emotional intelligence usually solves the cases.

“What endears us to him as a hero, particularly in this version, you draw close to him because you believe that he feels deeply, even if he doesn’t let on.

“That’s what’s happening a lot of the time. And also what makes it an extraordinary part to play. And also, to some extent, what makes it the perfect job directing.

“Because directing is about looking. Directing is about the gaze. When I’ve been well directed, I felt deeply, deeply seen.”

“Dalgliesh” S3 streams “Cover Her Face Parts 1 & 2,”  Monday on AcornTV