I'm not sure how Before Midnight will play to audiences unfamiliar with its two predecessors. Can the uninitiated catch up with Julie Delpy and Ethan Hawke's characters at this harder, decidedly less romantic juncture in their lives - he's a novelist, she's an environmentalist, and they are the parents of twin, towheaded girls - without experiencing both Jesse and Celine's heady Viennese walkabout (1995's Before Sunrise) and their rueful but beautiful Paris reunion (2004's Before Sunset)? Will Before Midnight mean anything?

I think so, but I can't say for certain, nor can the passionate cult of Before-istas who have followed Jesse and Celine over the last 18 years.

But what I can say is that Before Midnight, which finds the couple walking and talking, and driving and talking, and drinking and talking, and holed up in a hotel room and talking, offers a remarkably intimate and provocative study of a marriage. Here are a man and a woman caught up in the everyday realities of a relationship, rearing children, trying to balance careers with filial responsibilities, and wondering if they still love each other, or did they ever?

Of course, not every significant other gets to mull these matters - the mundane and the metaphysical - while they're vacationing at a to-die-for villa on the Peloponnesian coast of Greece. And that is where Jesse and Celine find themselves, guests of a sage old novelist (the cinematographer Walter Lassally) and a small coterie of family and friends. It is the couple's last few days after an extended stay, and Jesse has just bid his teenage son (a terrific Seamus Davey-Fitzpatrick) goodbye, taking him to the airport for the trip back to Chicago, where he lives with his mother, Jesse's ex.

And the return drive to this idyllic home - a long, extended take - finds Jesse suggesting that maybe they should move from Paris to Chicago, so he can be closer to his son. Which isn't what Celine, dedicated to her work, with a new post in her future, wants at all. By the time they pull up at the villa, the mood is sour.

Directed by Richard Linklater, as were Before Sunrise and Before Sunset, with a fluidity and grace that is exhilarating, Before Midnight is at once loose and improvisatory and diligently structured. Hawke, revisiting this keen if narcissistic American writer, displays an intense restlessness, and a humor that can turn quickly bitter. Delpy, as the hopelessly French Celine, is raw, wifty, passionate, and cuttingly smart. The two actors share the writing credit with Linklater - all of them clearly invested in, and deeply aware of, who these people are.

In a summer of numbing, effects-driven spectacle and formulaic blockbusters (and it's only the first week of June!), Before Midnight serves as an invigorating antidote. This is a movie that mines deep beneath the surface of human feeling. It will make you think - about love, about life, about two people who aren't real, except that they've become so for so many of us in this improbably successful indie franchise.

Contact Steven Rea at 215-854-5629 or srea@phillynews.com, or follow on Twitter @Steven_Rea. Read his blog, "On Movies Online," at www.inquirer.com/onmovies.