Humphrey Bogart and Lauren Bacall biography hints at infidelity within the legendary love story

"You know how to whistle, don't you Steve?"

That sexy bit of innuendo has long been etched in cinephiles' memories as the spark that lit the fuse of the legendary romance between classic Hollywood stars Lauren Bacall and Humphrey Bogart. Having met while making To Have and Have Not, the pair commenced an infamous love affair while Bogart was still married to his previous wife, Mayo Methot. They wed when Bacall was only 20 and Bogart was 25 years her senior.

Now, Hollywood historian William J. Mann probes their relationship in his latest book, Bogie & Bacall: The Surprising True Story of Hollywood's Greatest Love Affair, out July 11.

EW has an exclusive excerpt from the book, demonstrating that Bacall and Bogart's marriage was never as simple as a silver screen idyll. The passage unpacks Bacall's fascination with United States politician and presidential candidate Adlai Stevenson, reading between the lines of her memoir to understand their relationship.

In Bacall's own words, it's clear the two had, at the least, an emotional affair, if not also a physical one. An affair that Bogart was somewhat wary of. Read on for more below on this potential infidelity between indelible on and offscreen duo Bogie and Bacall.

In the fall of 1952, Bacall was told by a Hollywood producer, "If you're smart, you'll keep your mouth shut and take no sides" in the current presidential campaign. The controversy she and Bogie had stirred up five years earlier, when they'd flown to Washington to denounce the House Un-American Activities Committee, was still fresh. But Bacall refused. "What have things come to," she asked, "if I can't voice my preference for Adlai Stevenson?"

Bogie shared his wife's partiality for the erudite governor of Illinois and Democratic nominee. The Bogarts accompanied Stevenson on California campaign stops. For Bacall, the experience was thrilling. "Crowds waving and screaming—it made me feel I was running for office myself." She admitted to getting "pushy," refusing to allow anyone else in Stevenson's motorcade, including such fellow campaigners as Tony Curtis and Janet Leigh. After Stevenson and crew flew off to Texas, Bacall was still gripped by campaign fever and arranged to rejoin the candidate at a rally at Madison Square Garden in New York.

On the campaign train to Pennsylvania, while Bogart dozed, Bacall and Stevenson huddled in close conversation. "At every speech from the beginning—every platform, breakfast, lunch— Stevenson would catch my eye and wave and smile at me," Bacall wrote. "To my fantasizing mind he seemed so vulnerable." Such intimacy was bound to cause talk. Stevenson was the first major-party nominee to be divorced. His sister and official hostess, Buffie Ives, did not take kindly to the movie star latching on to her brother. "For glamour, the Democrats have beautiful Lauren Bacall," one newspaper observed. But for Ives, glamour led to gossip. Even the merest hint that Stevenson was flirting with Bacall would confirm many voters' suspicions of divorced men. She did her best to keep Bacall away from photographers. But she couldn't keep her away from the candidate.

By the end of the campaign, Bacall was thoroughly smitten. Stevenson, she believed, "needed a wife, someone to share his life with," and she seemed to wish that someone could have been her. In her memoir, she was remarkably candid about her feelings. "I fantasized that I would be a long-distance partner . . . a good friend he could feel free to talk with about anything." What she wanted was to be "connected with a great man capable of . . . bettering the world"—something her own husband, apparently, wasn't apparently capable of. "It takes one person," Bacall wrote, "who has real passion to unleash one's own comparable passions." Meeting Stevenson had fundamentally changed her life. "Something happened" inside her, she said, and she was never the same again.

Lauren Bacall and Humphrey Bogart are arguably Hollywood's greatest love story, but their relationship was nuanced and complicated. Bacall was 28 when she met Stevenson. She was just 20 when she'd married Bogie, who was 25 years her senior. Their legend would play down the personal cost of their age difference. When Bacall met Stevenson, she was in the prime of her life; Bogie had long since passed his. He was increasingly frail, years of heavy drinking and smoking taking their toll. Bacall had never been able to sow her oats the way Bogie had done in his own youth. She'd never had time to explore love or understand her own sexual and emotional power. So, she was doing that now, making her own decisions and establishing her own relationships, discovering that she liked being Miss Bacall at least as much as being Mrs. Bogart.

On election night, Bogie had a virus and stayed back at the hotel. Bacall did not stick around to care for him. "Having come this far," she wrote, "I was not about to miss anything." At the governor's mansion, the expectant jubilation quickly turned into despair as Eisenhower won in a landslide. Bacall was overcome as she listened to Stevenson make his concession speech. "I sobbed my way back to our room," Bacall wrote, where she found Bogie more upset about running out of quarters for the pay TV set than he was about the election. "Until Adlai Stevenson, I was a perfectly happy woman with a husband whom I loved—a beautiful son and daughter—some success in my work—a beautiful home—money—not a care in the world." But Stevenson, she wrote, "shook me up completely." On the flight back to L.A., "I was far away from Bogie," Bacall admitted, "my thoughts on the man I had left behind."

She was determined "not to have [Stevenson] vanish completely" from her life. Her husband was starting to object. "Miss Bacall supports wholeheartedly Governor Stevenson, up to the vomiting point," Bogie noted dryly to his friend and director, John Huston. During the campaign, Bogie had shared an idea with his wife for a cartoon: Bogie and their two kids would be at their front door. Stephen would ask, "Daddy, where's Mommy?" and Bogie would reply forlornly, "With Adlai."

Still, when Bogie was in Italy shooting Beat the Devil, Bacall flew to New York. At a party being given for Stevenson, she was "not at all sad to be the only Bogart present." After the soiree, the governor took Bacall on his arm and escorted her back to her hotel. In her telling of it, Bacall seems to have been hoping he would come upstairs with her. "I wanted to talk to him alone, to talk personally," she wrote. "Though I wasn't sure he would get that personal with me, the implication was that he would." If she made the offer, Stevenson declined.

Had she been prepared to begin an extramarital affair with Stevenson that night? A close read of her memoir gives the impression she was. "He did like to flirt," she wrote about Stevenson, "and he did know I was very young and had a solid crush on him." She made all the obligatory qualifications: "It wasn't that I was dissatisfied with Bogie or loved him any less [but] Stevenson could help a different, obviously dormant part of me to grow." In her fantasy, she could have it both ways: "Short of leaving husband and home—which I had no desire or intention of doing—I would see [Stevenson] when I could and keep the thread of my presence alive in his consciousness."

While in New York, the pair arranged to meet again in California, where Stevenson was giving a speech. At the designated time and place, Bacall was right up front. "Stevenson caught my eye—or I caught his—or we caught each other's," she wrote. They planned a rendezvous in Palm Springs, where the governor was heading for some rest. With her "imagination going at full tilt," Bacall headed out to the desert, her children left with nursemaids. "I was included in all his activities which only fed my fantasy," she wrote. She accompanied Stevenson to dinners with friends. If a sexual relationship developed between the two, it was likely there, in the shadow of the San Jacinto Mountains and far away from watchful eyes.

Bacall was eager to see Stevenson again, but Bogie, now home from Italy, declared, "Absolutely not!" Her husband's jealousy, Bacall wrote, "had come out before and would again. He held himself in check most of the time, but when it got to be too much, he let loose." She defied him and flew to Illinois, which was surely a sharp slap to Bogart's ego. Still, things didn't turn out the way Bacall wanted, either. Any hope for the sort of intimacy she had enjoyed with Stevenson in Palm Springs was dashed. Other people were always around. "All very proper," Bacall wrote. Buffie Ives was more hostile than ever, asking her "very pointedly" about her husband and children. "I was flattered that she might consider me a threat," Bacall wrote.

But the threat had likely been overestimated. The next day, on her way to the airport, Bacall stopped by Stevenson's farm in Libertyville to say goodbye. She found Adlai entertaining a woman, one of his "devoted followers," whose name she claimed not to remember. Although they exchanged warm farewells, the Bacall-Stevenson romance of the heart had come to an end. He had many women, and perhaps she had realized that. Although she would continue to speak highly of Stevenson and would support him for president again, the intensity of their interactions was now in the past. Bacall got onto the plane and returned to her husband and children.

When Bogie got sick a few years later, Bacall was steadfast; she really did love him, even if she wasn't always emotionally faithful to him. (There would be a similar infatuation with Frank Sinatra a couple of years after Stevenson, one that would linger past Bogie's death). But Bogart, too, had his own infidelities, turning to his old flame Verita "Pete" Thompson, closer in age and temperament to him, as Bacall began pursuing independent amours. Yet none of this should undercut the love story of Bogie and Bacall. Absolute fidelity need not be a requirement for true love. They believed in and boosted each other. In the beginning, Bogie had nurtured a young woman inexperienced with fame and public life. At the end, Bacall slept beside her eighty-pound husband in his hospital bed, tending to his bandages and massaging his feet. Hollywood tells stories that give us legends; the truth gives us human beings who have their own stories beyond the eyes of the world.

Excerpt from Bogie & Bacall by William J. Mann courtesy of Harper Collins.

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