Until betrayed by its essential docility, "The Promise" promises a fairly stimulating wallow in the tear-jerking depths. The premise is certainly calculated to trigger dramatic ironies of the most outrageously devastating kind. For a while I fancied that director Gilbert Cates had managed to recapture the ridiculous rapture of the Delmer Daves pictures - "A Summer Place," "Parrish," "Susan Slade," etal - that never failed to inspire sarcastic mirth back in my college days.

Nancy McCallister (Kathleen Quinlan), an art student who dabbles in dainty post-Impressionist canvases of her own, and Michael Hillyard (Stephen Collins), an architecture student who is also the scion of an architectural firm, are madly in love. They exchange vows at a picturesque promontory on the seacoast near Boston. Michael commemorates the occasion by placing the beaded necklace he has won for Nancy at a carnival beneath a handy rock.

Michael can't wait to break the happy news to his ambitious, widowed mother, Marion (Beatrice Straight), who is not overjoyed. She urges Michael to postpone marriage until the company's big new construction project in San Francisco is completed. When he balks, she springs a surprise of her own: a dossier from a private detective who has discovered that Nancy, an orphan raised by nuns, had a father who was killed in prison while serving a term for armed robbery and a mother who died of alcoholism.

Deeply offended, Michael decides to marry Nancy at once. While driving to the nearest justice of the peace with Nancy and his roomie Ben (Michael O'Hare), Michael is hit by an out-of-control lumber truck. Ben and Michael escape with knocks on the bean. Nancy isn't so fortunate. As a doctor grimly informs Mrs. Hillyard, "We've had to take over 90 stitches in her face, and . . . well, to be frank, there's not much left under those stitches."

Acting fast, Mrs. Hillyard takes advantage of her son's temporary coma to ease Nancy out of his life. "I will pay the cost of everthing," she says to ther disfigured girl. "It will be well over $100,000."

Through her plaster facemask the heroine replies, "I can't accept such a gift."

Narrowing her eyes, Mrs. Hillyard explains, "Gift isn't precisely the word. . . "

Before Michael comes to, Nancy is on her way to San Francisco, of all places, to undergo a year of painful, painstaking operations and psychiatric therapy paid for in advance by Mrs. Hillyard. Nancy has promised to stay out of Michael's life forever. Mrs. Hillyard leads Michael to believe that Nancy was killed in the accident, a wobbly fiction on at least two counts: Many more people at the hospital would have to know the truth about Nancy, and upon recovery Michael is headed straight for San Francisco to supervise the big project.

For some reason actresses often believe that roles as grotesquely mawkish and contrived as Nancy offer an irresistible histrionic challenge. More often than not they prove embarrassments. Quinlan, a fascinating doe-eyed ingenue in "American Graffiti," "Lifeguard" and "I Never Promised you a Rose Garden," does nothing for herself by traversing the range required by "The Promise." A demure twerp at the outset, she emerges from two reels with her face under wraps to project not touching vulnerability but glaring fashionability, as if she expected to be addressed as "Imperious Princess of the Darkroom."

Nancy, you see, celebrates her new face by turning to photography. Needing a giant photomural for his building and coincidentally attracted to her photos, Michael keeps nagging the new Nancy, who calls herself Marie Adamson (Eve Adamson would be better) until he catches on in time for a fade-out reunion at their hallowed rock.

It is a delightful stroke to have Michael see the light of day by glimpsing Nancy's painting on the doctor's wall. It's even better when Laurence Luckinbill, who plays plastic surgeon, floors Michael, an uninvited intruder, with a single punch. Those plastic surgions are handy with their dukes, it appears. Collins also makes Michael more appealingly earnest than such an out-of-it hero has a right to be, and Beatrice Straight is a formidable presence as Mrs. Hillyard. A proud, ruthless obstatcle to dopey young love, she recalls Agnes Moorehead and Judith Anderson at their most regally sinister. CAPTION: Picture, Kathleen Quinlan and Stephen Collins