It's 1939 on the very eve of declaration of War in London. Oxford don C. S. Lewis (Matthew Goode) calls upon Sigmund Freud (Anthony Hopkins) at his invitation. He passes Anna Freud (Liv Lisa Fries) as she goes out to lecture and ponder whether she will reveal her lesbian affair to her father. Meanwhile, the two men attack each other's philosophical beliefs.
And that's what the movie is, two men talking, interrupted occasionally by flashbacks to their younger days and air raid to lend this stage play some cinematic credibility. In this made-up scenario -- although the story is that an Oxford don visited Freud shortly before his death, the claim, as here, that it was Lewis, is a fabrication of the play and movie -- they argue around each other, and finally agree only that people are afraid of death.
The rest of it.... well, Freud's beliefs are at the end of his life (he died three weeks after the supposed events of this film), while there are plenty of things that Lewis did say until twenty years after. As for the basic disagreement about religion versus science, that's a non-conflict; as smarter people than I have declared, science is about how, not why. If G*d created the universe we live in, thanks a lot.
Both men are fine actors and easily translate the script into natural-sounding words. I have no idea if Hopkins' accent is a good representation of the Viennese one; Kohli Calhoun is listed as the dialect coach.