THE RUNNER STUMBLES -- AMC Carrollton, AMC Skyline, K-B Cinema, Roth's Parkway, Roth's Tysons Corner and Springfield Mall.

Love story, murder mystery, psychological study -- "The Runner Stumbles" is an ambitious film that achieves excellence on serveral levels.

Despite the subject matter -- it's based on a 1920s Michigan case in which a Roman Catholic priest stood trial for the murder of a nun -- the film is anything but sleazy. This is an intelligently written, capably acted and meticulously crafted movie which goes to great lengths to avoid sensationalism. mHumor and compassion keep it lively and unpretentious.

At its simplest level, the film is about a priest and a nun who fall in love. But as the title implies, "The Runner Stumbles" goes deeper and explores what can happen when a man who had dedicated his life to God sees that commitment threatened by human love.

Dick Van Dyke gives a superb against-the-grain performances as Father Rivard, a cynical priest the church has banished to the dying town of Solona, Washington, for the radical activities of his youth. This is Van Dyke's first major dramatic role, and you keep waiting for him to trip over a footstool or something; but by the end of the movie, when we see him overcome with emotion at his trial, he's thoroughly believable.

As the bubbling, enthusiastic Sister Rita, Kathleen Uinlan is a bit too sunshiny. When Van Dyke grumps that he's never seen a rainbow in Solona, she tells him, "You just have to know where to look." She's never seen without a bouquet of wildflowers and spends a lot of time frolicking with the schoolchildren. But to her credit, when Sister Rita and the kiddies skip merrily over the mountainside, they sing a catchy little number called "My Rumble Seat Gas" instead of "Do-Re-Mi."

In the classroom, too, Sister Rita is shockingly progressive: she teaches creative writing and art appreciation, pretty advanced stuff for small-town parochial schools in the '20s. In fact at times Sister Rita sounds as if she came to Solona by way of Esalen. "Talk it out," she urges everyone. "Go ahead and cry, you'll feel better." She doesn't tell them go get in touch with their feelings, but you wouldn't be too surprised if she did.

A little restraint would have made her more convincing. Her infernal optimism can be blamed on the inexperience of youth, but that doesn't explain why we never see her praying.

Father Rivard and Sister Rita fall in love, but since this is the '20s and not the '70s, they don't run off and get married. They agonize, deny themselves. Their consciences paralyze them.

For a time, Father Rivard's solution is to avoid the nun completely. The way he deals with his temptations -- actually sublimating his personal desires because he once took a vow of chastity -- makes him seem like something from outer space. Sin? Guilt? Conscience? They're like words from another century. And that's what makes this romance so compelling.

Technically, the movie is near-perfect. It was shot on location in the old mining town of Roslyn, Washington. Every weathered board, wildflower and winding road is bathed in golden light and photographed in loving detail by Laszlo Kovacs.

Beau Bridges as Rivard's alcoholic attorney, Ray Bolger as the rigid monsignor and Tammy Grimes as the town spinster all measure up to the standards imposed by producer-director Stanley Kramer. And Maureen Stapleton almost steals the show from Van Dyke in her role as Mrs. Shandig, the disturbed, devoted rectory housekeeper. Her anguish and confusion as she watches the affair progress is moving.

As a romance, "The Runner Stumbles" is an affecting story. With the added moral and psychological dimensions, it also is a powerful one.