The voice that giggles off the page in her new memoir is unmistakably Geena Davis — funny, frank, and self-effacing, a tall woman and towering talent with a lifelong girlish streak. She is Thelma without the hellion’s drawl, Dottie Hinson, blocking home plate, daring you to run on her, Barbara in “Beetlejuice” adjusting to her newfound, dead state, with a little Valerie — coy and apple-cheeked cute making one wonder if indeed, “Earth Girls are Easy” — thrown in for sex appeal.

But this just-revealing-enough memoir is designed to make one reconsider her glamorous screen persona, and the offscreen focus that allowed Oscar winning actress, activist and accomplished archer (in her ’40s) to be a success in spite of the self-conscious-about-her-height, self-doubt and enforced humility of her upbringing.

An early anecdote recalls how Davis’ Massachusetts family was so “polite” they’d almost let a distracted, careless-driving relative plunge them into oncoming traffic and fiery deaths rather than speak out and risk being thought of as “impolite.”

The modest, chipper, upbeat image that she trots out for chat shows, book tours and speeches on behalf of her Geena Davis Institute on Gender in Media is a lifelong construct, and makes her standout in a business bent on rewarding “chutzpah.” Not that she doesn’t have that, too. She arm-twisted her friend Lawrence Kasdan for the role that made her and earned her an Oscar, “The Accidental Tourist.” And Madonna probably never got over her nudging her aside to star in “Angie,” a hot, working class New York script making the rounds as “Angie, I Says.”

But the lady who liked being known as “the nicest person on set” in all her movies — save for “A League of Their Own” (“You simply can’t out-nice Tom Hanks.”) let herself get pushed around a lot over the course of her career– bullying power games with directors and co-stars, harassing come-ons in auditions and the like. That compulsion is to “be nice,” polite, “not cause a fuss” or bring attention to herself gave her trouble, but she never grew out of it.

There was this one time I drove to Atlanta to interview her that came to mind while reading “Dying of Politeness.” The interview kept changing times and locations, something almost impossible to cope with pre-cell phones. And this was after I’d left at 5 in the morning to get there at the tail end of her local morning shows and a midday show or two round of chats.

Atlanta pre-GPS was a pre-Sherman nightmare of “Peachtree” this or that and murderous traffic. Every time I’d stop to ring up the PR firm running her schedule, I had somewhere else to go and some new time.

The last change was literally at the last minute. The damned Atlanta Hard Rock Cafe had a kitchen fire than emptied the place and shut it down.

I finally connected with Davis in the lobby. While she hadn’t had to do her own driving in that maze of Peachtrees, she was unflappable, smiling and laughing about the day’s mayhem. Yes, I was late. No, she hadn’t left. Told the publicists to rebook her flight. Wouldn’t have been polite, so yes, she’s that nice.

Making movies became her on-the-job “therapy” for her bending-over-backwards/go-along-to-get-along tendencies. Prickly, brooding, deep-into-character Oscar winner William Hurt is demanding meetings with her and adapter/director Kasdan, trying to rein her in and control her performance?

“Just tell him to go f— himself,” “bad ass” co-star Kathleen Turner advised. Her first-time acting coach, analyzing the script, the character, Hurt and Davis, said “You’re going to stand too close to Bill,” invade his space, answer his snappish moments with a joke. You can see it in the movie. This upbeat dog trainer rattles the divorced and grieving “accidental tourist” out of his funk.

She took a lot of Bill Murray’s boorishness making “Quick Change.” But pairing her up with “my ride or die,” Susan Sarandon in “Thelma & Louise” taught Davis to be assertive and let her feminist flag fly. She was never the same after that. “Bad Ass” became her goal.

As with a lot of actor memoirs — the recent one by Hugh Bonneville especially — Davis brushes past or simply avoids a lot of personal life details. We hear about the “magical” relationship with Jeff Goldblum, her co-star from “The Fly,” “Earth Girls are Easy” and “Transylvania 6-5000,” but not what ended the marriage. She’s four-times divorced, so that’s a lot to leave out.

For all the self-assuredness she says she lacked, she had the confidence to leave college, move to New York, become a model, get cast in “Tootsie” and gee whiz her way into sitting next to Sidney Pollack on set every day, mentored into the movies by one of the giants of the business. Yes, beautiful starlets are a privileged class. But her path to stardom has a hint of “just as I planned it” about it.

The TV series she’s done, from “Buffalo Bill” to “Commander in Chief,” get short shrift. But she gives us a glimpse of what her last two decades of off-camera work have been. They’re what earned her a second Oscar, the Jean Hersholt Humanitarian Award for directing studies about gender representation in the media, working to make things easier for actresses of all ages, especially the ones coming up after her.

And to think she managed all of this without losing her self-effacing modesty and good manners. Let’s hope she asserts herself enough to get that “League of Their Own” sequel she craves in the works. “A Little League of Their Own” sounds like a winner. Coming from Geena Davis, we’d expect nothing less.

“Geena Davis: Dying of Politeness,” by Geena Davis. 271 pages. HarperOne Publishers. $28.99