Black Narcissus, the BBC’s three-part grown-up Christmas drama, begins with a jolt: the sight of Diana Rigg in the final TV performance she filmed before her death in September. (She’s also in an Edgar Wright film, Last Night in Soho, due for release next year.) Sadly, she doesn’t have much to do, although her presence is as welcome as ever. It’s 1934, and an old general, Toda Rai (Kulvinder Ghir), has donated a rundown palace in the Indian Himalaya to The Sisters of St Faith in Calcutta. He wants them to set up a convent school there, in the hope their work will excise the tragic memory of his sister, who fell to her death 20 years before. As the old Mother Dorothea, Rigg gives Gemma Arterton’s Sister Clodagh her orders, with grave misgivings. “I don’t think you’re ready for it,” she says. “I think you’ll be lonely.”

They’re wise words, as it turns out. But Clodagh is ambitious and proud, tricky qualities for a nun, and sees Mopu as an opportunity to feather her wimple. With her Sister squad: Briony (Rosie Cavliero), Philippa (Karen Bryson), Blanche (Patsy Ferran), and Ruth (Aisling Franciosi), she sets out on her mission with a word of warning from Father Roberts (Jim Broadbent) ringing in her ear. It won’t be easy. A German group has recently tried and failed on the same site.

It doesn’t take long for the scale of the undertaking to become obvious. Despite its spectacular location on a dramatic cliff-edge, Mopu is an oppressive, haunted place where the locals are understandably wary of more outside meddling by these would-be white saviours. The only support comes in the form of Mr Dean (Alessandro Nivola), the general’s agent, a rugged Indiana Jones-type who fixes the loo and wastes no time in making it clear he, in his own way, would also like to feather someone’s wimple. Possibly Ruth’s. She’s most flustered by his presence.

Were you writing the blurb, you would say the stage is set for a darkly erotic battle between duty and desire, against the background of the uneasy dynamic between missionaries and their intended converts. There has already been a well-regarded film adaptation from 1947, so the bar for a new version is even higher. The creators have said they’ve gone back to Rumer Godden’s 1939 source novel. It’s a pity their version, although shot in an unsettling mountain chiaroscuro and with solid performances, struggles to achieve the required intensity. Arterton does her best with a tricky part, which calls for her to simultaneously be a credible religious sister and a desirable romantic lead. Through flashbacks we see glimpses of her life before she took orders, but they don’t create enough of a sense of internal conflict within her. Take a scene where Dean catches her looking out of the window.

“One’s eyes adjust eventually,” Dean says.

“Custody of the eyes,” Clodagh replies. “We learn it as a novice. It’s part of the rule. Not to look unless you need to.”

“A way to keep the gaze inward.”

“One’s eyes adjust eventually.”

It ought to be a slow burn, but instead it just feels slow. Dame Diana deserved a finer farewell. She’ll be missed. 

Black Narcissus concludes on Monday and Tuesday (28-28 December) at 9pm on BBC One