“The Invisible Woman” opens Friday at Sundance Cinemas. I’ll be hosting a post-show chat after the 7:10 p.m. Tuesday, April 29 show at the theater. R, 1:51, three stars out of four.

Charles Dickens was a man of the people. In addition to writing stories that changed literature, he was an enthusiastic playwright and orator, championing the plight of the downtrodden in England. In one scene in “The Invisible Woman,” we see Dickens (Ralph Fiennes, who also directs) springing to action after a horrific train accident, quickly taking charge to tend to the wounded.

He may have been a man of the people, but not necessarily a man of one person. “Invisible Woman” tells the story not of the public Dickens but of the private one, one who carried on a clandestine affair with an actress, Nelly Ternan (Felicity Jones) for 13 years until his death in 1870. He was often callous in trying to keep the affair a secret — Ternan was with him during the train crash, but he told the authorities he was traveling alone.

But Fiennes doesn’t treat Dickens as a monster, but as a deeply flawed man who seemed to have equally deep reservoirs of generosity and selfishness. “Invisible Woman” is a sensitive and even delicate observation of a love affair between two lonely people. Several times, Fiennes shoots Nelly wandering along a vast expanse of beach, not another soul in sight. And at one point, he twins that shot with a similarly composed one of Dickens speaking before a large audience, the faces all indistinct blurs. In his own way, he’s just as isolated as Nelly on that beach.

The film is largely a flashback, as an older, married Nelly begins to revisit her memories of Dickens. As a 17-year-old obsessed with Dickens’ work (“It changes us!”, she says excitedly), Nelly and her family become friendly with the exuberant Dickens during rehearsals for one of his productions. Nelly’s mother (Kristin Scott Thomas) senses the attraction between them but seems to acquiesce, knowing the patronage of a famous author may give Nelly financial support in a perilous time. Dickens’ wife (Joanna Scanlan), who has grown apart from her husband after bearing him 10 children, also sees it, but says nothing.

Fiennes teases out the will-they-or-won’t-they tension of Charles and Nelly for the first hour of the film — this is Victorian England, after all. And even when the couple finally consummate, Dickens is willing to separate from his wife but not divorce her, leaving Nelly in the shadows. He seems terrified of losing the goodwill of his adoring public — who his wife tells Nelly, in one pointed scene, is his one true love.

“The Invisible Woman” moves slowly at times, as befits the rhythms of its age. But the pleasure and the drama come in watching for the real emotions peeking beneath the fancy costumes and flowery dialogue (by screenwriter Abi Morgan), all the more fierce because they must be repressed. Fiennes proves himself to be an attentive director, clued into to the nuances and complexities of each performance. Jones (“Like Crazy”) makes the biggest impression as her character evolves from starry-eyed fan girl to grieving ex-lover, but the entire cast is strong.