“Freud’s Last Session,” starring Anthony Hopkins as Sigmund Freud, adds to a string of sterling late-chapter performances by the 86-year-old actor. He was the soul of “Armageddon Time,” the reason to see “The Father” and the papal foil to Jonathan Pryce’s Pope Francis in “The Two Popes.” With the exception of James Gray’s more cinematically composed “Armageddon Time,” the movies have offered simple, stagy showcases for Hopkins, a lion in winter.

“Freud’s Last Session” also comes from the stage and, like “The Two Popes,” centers on the tete-a-tete of intellectual opposites. Mark St. Germain’s 2009 two-character play brought together Freud and C.S. Lewis (played by Matthew Goode in the film) for a speculative meeting in 1939 London.

An aged Freud, suffering from oral cancer, prepares to receive the Oxford academic at his London home while war with Germany is growing inevitable. The factual jumping-off point is that Freud, three weeks before his death, is recorded as meeting with an unnamed Oxford don. As Freud’s daughter Anna (Liv Lisa Fries) prepares to leave in the morning, he mentions Lewis’ impending arrival. “The Christian apologist?” she responds. “Yah,” he chuckles.

Their conversation, which makes up the bulk of the film, imagines a spiritual debate between the father of psychoanalysis, a proud atheist and man of science, and the theological Lewis, a believer who in the years after “Freud’s Last Session” takes place would pen his Christian apologetic novel “The Screwtape Letters” and, later, the fantasy parables of “The Chronicles of Narnia.”

If their adverse positions didn’t make for enough drama, air raid sirens are sounding (Hitler has just taken Poland) and Freud’s health is bad enough that he, in between dripping morphine into his whiskey, several times eyes a suicide pill during the day. Death and history buffer their talk of God, fear and pain.

But the elements never quite cohere in “Freud’s Last Session.” The rhythm of conversation feels choppy and lacks the probing give and take that can electrify a two-hander. Freud — or is it Hopkins? — so dominates their talk. Goode, with less to chew on, remains more observational and removed for his Lewis to ever fully engage Freud.

Director Matthew Brown, who shares screenwriting credit with St. Germain, has artificially “opened up” the play to include flashbacks and side plots, most notably that of Anna, whose extreme devotion to her father factors into Freud’s discussions of sexuality. Yet Anna’s story, including a relationship with a woman, Dorothy Tiffany Burlingham (Jodi Balfour), not acknowledged by her father, is too complex to graft into the theological debate. It feels like a movie in its own right. That “Freud’s Last Session” is overly murky in shadows also contributes to the movie’s lack of clarity.

But Freud and Lewis’ dialogue sometimes finds compelling points of commonality. Fantasy figures prominently into both minds — Freud in his analysis of dreams and Lewis in the dreamworlds he’ll create. And both come to their beliefs in part from childhood experiences that color their lives. “I have only two words to offer humanity: Grow up,” says Freud.

And Hopkins remains riveting. Some three decades after memorably playing Lewis, himself, in 1993′s “Shadowlands,” he now plays across from the novelist, adding to the poignancy of the movie.

But I suspect my memory will bleed some of these late films of Hopkins’ together. In each, he grapples with a life of accomplishment just as he does present pains and joys. He might be plucking an azalea in “Freud’s Last Session,” or watching a grandson fly a model rocket in “Armageddon Time.” But each performance crackles with wit, wisdom and playfulness in the face of the inevitable. They add up to a wistful cycle of films of big questions and small moments.

“Freud’s Last Session” — 2 stars (out of 4)

MPA rating: PG-13 (thematic material, some bloody/violent images, sexual material and smoking)

Running time: 108 minutes

How to watch: In theaters Jan. 4