Written by Lupino and Young, “Never Fear” is a tough-minded, modest, yet memorable film about a profound existential struggle. The arc of its rehabilitation narrative is largely familiar; it was released amid a clutch of movies about disabled veterans like “The Men” (1950), Marlon Brando’s big-screen debut. For inspiration, Lupino drew on a physiotherapist she had known at the real rehab center where the movie was set, the Kabat-Kaiser Institute in Santa Monica, Calif. She also probably borrowed from her life, having contracted polio when she was 16 and under contract at Paramount. (Because of a set accident during “Never Fear,” she directed from a wheelchair.)

“Never Fear” has an attractive no-frills look that fits the story and its modesty, and is in keeping with Lupino’s embrace of documentary realism. Working with a cast that includes actual patients and largely avoiding glamour (except in the hair and makeup), she whittles the story down to basics and mainly focuses on the rehabilitation and Carol’s emotions. Although never less than sympathetic, Carol isn’t picture perfect; she doesn’t suffer beautifully or pacifically. She frets and fights, and lashes out at Guy and often at herself. She also starts a needy flirtation with another patient, Len (a suave Hugh O’Brian in the film’s strongest performance), whom she clings to as her worries about her progress escalate.

Much of “Never Fear” unfolds indoors, which gives it a claustrophobic quality that dovetails with Carol’s sense of feeling trapped, and comes out in jolts of anger, panic and self-pity. Perhaps it’s no surprise that Lupino, a tough number — and a memorable, complicated presence in noirs like “High Sierra” — has little patience for Carol’s despair. The movie’s attitude toward its protagonist is fiercely devoid of sentimentalism and, at times, flat-out disapproving. In one bracing scene, Carol, now in a wheelchair, shrieks “I’m a cripple!” at Guy, an explosion that provokes a withering rebuke from two lovers, one a man on crutches who firmly puts that self-pity in its place.

Forrest and Brasselle are never quite as good as you want them to be, though both have their moments, especially when their characters are most tightly wound. (From some angles and in certain lights, Forrest can resemble Lupino, who cast her in other films.) Some of the more haunting performances happen around the edges: The look of contempt that the woman with the man on crutches gives Carol resonates long after the scene has ended, deepening the story’s emotional colors. And an aching sequence with Guy and another woman, a would-be fling (a touching Eve Miller), condenses a movie’s worth of adult desire and regret into the melancholy that settles in her face.

“Never Fear” is sprinkled with scenes shot outdoors that deepen its textured realism, including a picnic for the patients, their friends and others. (While Lupino was directing her first film, she admiringly spoke about the neorealist god Roberto Rossellini.) Here, as elsewhere, Lupino underscores the ordinariness of these men and women, some of whom are in wheelchairs while others relax next to them. She matter-of-factly conveys disability in intimate moments of rehabilitation — in close-ups of Carol’s body moving and being coaxed to move — and when she goes big and wide for an exuberant square dance in which the revelers do-si-do in wheelchairs, joyously independent.