“My summer has stayed with me all my life,” muses the narrator of the melodrama “Saving Grace B. Jones.” “If you saw that summer in a movie, you’d never believe it really happened.” True enough.

That girlish voice belongs to the actress Connie Stevens, now 74, making her directorial debut with a semi-autobiographical film completed in 2007. In the screenplay, written by Stevens and Jeffry Elison, she is the grown-up voice of Carrie (Rylee Fansler), looking back to a summer in the early 1950s, when, after witnessing a murder, she was sent from Brooklyn to live with friends of her father’s, Landy (Michael Biehn) and Bea (Penelope Ann Miller), in Boonville, Mo.

Shortly after Carrie arrives in Missouri, the husband retrieves his unstable sister, Grace (Tatum O’Neal), from a mental hospital where she has been for 17 years. From the glimpse we have of the place, with its head nurse played by Piper Laurie as a grim destroyer of lost souls, it is a chamber of horrors.

O’Neal’s Grace is a fluttery Blanche DuBois type who transforms into a ranting madwoman wreaking havoc. Instead of an ax, she wields scissors. From here on, the movie is a grotesquely overacted, ineptly staged screamfest.

The freakout by Grace coincides with a catastrophic flood, during which a boating accident unleashes her demons. Until then, O’Neal has her moments, but the decision to portray her as a raving maniac yields diminishing returns. Eventually, when everyone is yelling while it rains buckets, you want to put your fingers in your ears and howl, “Enough!”

(At the Screenland Crown Center.)