Toward the end of the movie Mamma Mia!, Meryl Streep sings, with her long-lost love (and new husband), Pierce Brosnan,

In our lives we have walked some strange and lonely treks

Slightly worn but dignified and not too old for sex

Well, she should know. If there is any actress today teaching all of us that you can’t be too old for sex, it’s Meryl Streep. She makes that point as the “dancing queen” Donna in Abba’s musical, the divorcée in a love triangle in It’s Complicated, and in her latest movie, Hope Springs.

In Hope Springs, Streep is paired with a rather gruff and scraggly Tommy Lee Jones. Nebraska couple Kay and Arnold have been married for 31 years. “Thirty-one years!” Arnold pronounces more than once. To him, a tax accountant by trade, the sheer number is proof that there is nothing wrong. Kay, on the other hand, wistfully yearns for a “real marriage” again. One that includes intimacy, affection, and—yes—SEX.

The first scene in the movie shows Kay primping tentatively in a bathroom mirror. She tousles her hair and smoothes her silky nightgown before steeling herself and entering her husband’s separate bedroom. When he realizes what she has in mind, he mutters a half-baked excuse (something about having had pork for lunch), and she retreats in a humiliated hurry.

The scene is funny. But it is heartbreaking.

Her next step is the “Self Help—Relationships” aisle of the nearest Barnes & Noble. There she discovers Spice Up Your Marriage, by Dr. Bernard Feld, which she devours in the store’s parking lot. Emboldened by what she perceives to be her last chance, Kay cashes in a CD (“my own money”) and books a trip for two to Great Hope Springs, Maine, for Dr. Feld’s Intensive Couples Counseling. When Arnold, grudgingly, gets on the plane, their real work—and our genuine enjoyment—begins.

The week in Maine, we learn, will include morning counseling sessions, followed by free time and homework assignments. Great Hope Springs gives us a typical Maine lighthouse, sailboats, and rocky beaches (although the movie was actually filmed in Connecticut), and a small supporting cast of salty characters. But these are presented with a refreshingly light touch, starting with the no-nonsense diner waitress to Elizabeth Shue as a funny and emotionally supportive bartender. The entire town thrives on the conjugal tourist trade the famous “Dr. Bernie” draws.

Steve Carrell is just right as the therapist (or “Quack!” as Arnold assumes and asserts). He is straightforward, intense, and interested, and his sessions with Kay and Arnold are among the best scenes in the film. The body language is priceless! Watching Streep and Jones squirm on Dr. Bernie’s couch makes it easier for the audience to sit through some fairly squirm-worthy topics. Like fantasies, oral sex, and masturbation. These are subjects we now expect to find in the next installment of The Hangover. What’s new is the age and utter ordinariness of the couple who are talking.

It’s risky business, and in less capable hands might have been an embarrassing flop. But over and over again, Hope Springs is a pleasant surprise.

The screenplay is the first feature film from television writer Vanessa Taylor, whose credits include Game of Thrones and Everwood.  Although she herself is younger and unmarried, she has painted a touchingly accurate portrait of a marriage in meandering decline. Hope Springs was directed by David Frankel, who worked with a very different incarnation of Streep in The Devil Wears Prada.

Both the writing and the direction are top-notch. But the true magic comes from the film’s two stars. Meryl Streep’s performance is so candid, at times almost naked (although for a movie all about sex, there is virtually no nudity whatsoever). And she seems to have gently teased out the most sensitive performance I’ve ever seen from Tommy Lee Jones. The word for both actors is simply courageous.

In the course of the movie, Kay steps further and further out of her comfort zone as Arnold very gradually (and quite against his will) starts to open up. We realize that there are two sides to any argument. And to any marriage.

The only fault I had with Hope Springs was the soundtrack. While the acting is so natural it borders on non-acting, the music is forced and, in several scenes, too loud and too long. For me, it interrupted what was a very intimate experience.

So intimate, in fact, that there are moments when the audience feels a bit voyeuristic and downright uncomfortable. There are two reasons for this. It’s a result of the personal scenes we are watching and listening to. But it’s also because of the overarching theme of the movie. Should people who are no longer young and slim and unwrinkled talk so much about—much less engage in—s-e-x?

Take it from Dr. Bernie and, after a bittersweet struggle, Kay and Arnold . . . the answer is Y-E-S!