By Chris Nashawaty
August 13, 2014 at 07:50 PM EDT
Warner Brothers/Getty Images

With her sleepy, seductive eyes and patrician, pack-a-day voice, the actress enters the room of Humphrey Bogart’s world-weary fishing-boat captain, Harry Morgan. She calls him “Steve” even though that is not his name, and offers him money to help him get out of a fix—we get the impression that it’s merely the latest in a long line of fixes resulting from hard luck and muddled politics that Bogie’s character will have to get out of. He stubbornly refuses her offer. Pride and all that. She falls into his lap and plants a kiss on his unexpecting lips. She pulls away. “What did you do that for?” he asks. “Been wondering whether I’d like it,” she replies.

Later, as she’s leaving his room, she delivers an exit speech for the ages: “You know, you don’t have to act with me, Steve. You don’t have to say anything, and you don’t have to do anything. Not a thing. Oh, maybe just whistle. You know how to whistle, don’t you, Steve? You just put your lips together and… blow.”

“Just put your lips together and… blow.” As the words come out of her mouth, every man and woman in the audience is leaning forward in their seats, thinking the same exact thing: Who is this woman? It is 1944. She is 19 years old. And with that one indelible scene of serve-and-volley flirtation, her life is about to change forever. She will not only become a movie star from this moment forward, her kiss will force the biggest big-screen icon of his era to leave his wife and ask her to marry him despite their 25-year age difference.

But we’re getting ahead of ourselves. Let’s back up….

Before she was Lauren Bacall, she was Betty Joan Perske. A leggy beauty born to Jewish parents in the Bronx with a brassy, take-no-guff sense of a life already lived. Experience. It was an act, of course. Betty was innately shy and insecure—the tough exterior was merely a facade—the first evidence of her underappreciated gifts as an actress. As a teenager, she was obsessed with the movies of Bette Davis. So she began studying acting at the American Academy of Dramatic Arts in New York. Kirk Douglas was a classmate. At 18, she landed her stage debut in a play that closed before it even opened. Devastated, she turned to modeling, where in March 1943, she lands on the cover of Harper’s Bazaar. Nancy “Slim” Hawks, the wife of director Howard Hawks, sees the magazine and stops in her tracks. She shows it to her husband who didn’t need to be convinced that the model had something special. He brings Betty Joan Perske and her mother out to Hollywood and signs her to a seven-year contract. There, the Hawkses groom the ingenue for the silver screen. They rechristen her “Lauren Bacall” (the last name taken from Betty’s mother’s maiden name, Bacal). They teach her how to lower her vocal register to give it that smokey, come-hither tone. Then, most fatefully of all, they cast their discovery in Hawks’ next film, 1944’s Hemingway adaptation, To Have and Have Not. In a different—and better—era in Tinseltown, this is how it was done.

Bacall’s costar in the film is Humphrey Bogart, the brooding, macho star of The Maltese Falcon and Casablanca. He is 44. Old enough to be her father. But not too old to be able to ignore the seductiveness of the woman standing next to him. She’s a knockout, to be sure. But more than that, she gives as good as she gets. Sparring with her is like going 12 rounds with Joe Louis. It’s like catnip. Bacall is terrified of her first movie role. She can barely hold a match to light her cigarette without trembling like a leaf. In take after take, she tilts her chin downward, burying it into her chest to steady her nerves, while lifting her eyes up—a pose that manages to convey both sexiness and street smarts. It will later be called “The Look.”  Watching the movie, you would never guess she is anything other than defiant and confident. She’s hypnotic.

Let’s back up one more time and talk about that kiss. The nonchalance with which she slips into his lap, calls him a “stinker”, and plants one on Bogie’s grizzled mug. She’s doing the driving here. And when it’s over, he asks, “What did you do that for?” As if a woman like this needed a reason! She wanted to see if she’d like it, naturally. He needs to know: “What’s the decision?” Like a kitten toying with a ball of yarn, she purrs, “I don’t know yet…” And goes in for seconds. At that moment you can see the coolest man on the planet losing his cool. He is smitten and the camera is still rolling. Afterwards, she gets up and coyly says, “It’s even better when you help…” then heads for the door for her date with Bartlett’s Book of Quotations history with her line about knowing how to whistle.

It wouldn’t be Bogie and Bacall’s last kiss. You could say they were just getting started. During filming one night, Bogart stopped outside of Bacall’s trailer to say goodnight. And he leaned over and kissed her. The cameras weren’t rolling this time. And now he was in charge. Or was he? Within three weeks, the two costars were in the throes of a torrid affair, ending with Bogie leaving his third wife (Mayo Methot) and asking Betty Joan Perske to be his fourth. They would make three more films together: 1946’s The Big Sleep, 1947’s Dark Passage, and 1948’s Key Largo.

You could say that the history of movies is comprised of moments like this one. A string of unscripted, stolen moments sealed with a kiss. And yet, we rarely believe them. We rarely lose ourselves in them and forget we’re watching actors pretending. There is nothing make-believe about the moment when Bacall met Bogie in To Have and Have Not. And yet, it’s pure celluloid magic sprinkled in fairy dust. It’s for the ages. It’s a snapshot of two actors not acting. They are just living in the moment, falling in love in front of our very eyes. How lucky we were—and are—to be able to witness something as miraculous and timeless as that.