At a prestigious awards ceremony, the theatrical elite gathers to celebrate one of their most dazzling new stars: the extraordinary young Eve Harrington (Anne Baxter), whose unparalleled ascent to fame has captivated many. Among the attendees are notable figures from the theater world, including the renowned director Bill Simpson (Gary Merrill), the accomplished playwright Lloyd Richards (Hugh Marlowe) and his wife Karen (Celeste Holm), alongside the luminous Broadway icon, Margo Channing (Bette Davis). As they gaze upon Eve, their expressions reveal a mix of skepticism and disdain. Off to the side sits the infamous theater critic, Addison DeWitt (George Sanders), who, with an amused demeanor, begins to recount Eve's intriguing journey.
Not long ago, Eve was merely a starry-eyed admirer who haunted the theater's stage door, yearning for a fleeting glimpse of her idol, Margo Channing. When brought into Margo's orbit by Karen, Eve gushes with gratitude and humility, swiftly embedding herself as a general assistant in Margo's busy life. She impresses Margo's partner, Bill, as an innocent and eager girl eager to help out. Eventually, Eve finds herself living in Margo's home, answering phones and serving breakfast in bed. However, Margo's maid, Birdie (Thelma Ritter), grows increasingly wary of Eve, sensing her unnerving tendency to scrutinize Margo closely.
With Birdie’s cautioning in mind, Margo becomes suspicious. While everyone else assures her of Eve’s goodwill, Margo’s intuition tells her to stay alert for potential schemes. During Bill's birthday party, after one too many drinks, Margo lashes out at everyone around her. Later, Eve confides in Karen, seeking her help to win a coveted role as Margo’s understudy in Lloyd’s new play. Karen agrees, believing it could benefit them all.
Eve soon seizes her chance. Margo, known for her tardiness, misses a read-through, allowing Eve to shine in her absence, leaving even Addison DeWitt impressed and intrigued. A new star is rising, but Margo, feeling overshadowed, confronts Bill, leading him to consider leaving her. Karen and Lloyd also express their frustrations with Margo, creating a rift within their camaraderie.
An unexpected empty gas tank keeps Margo from returning in time for a performance, allowing Eve to take the stage. Impressed, Addison DeWitt begins to closely follow Eve's burgeoning career. Outside her dressing room, he overhears Eve attempting to woo Bill, who ultimately rebuffs her advances, prompting DeWitt to step into the picture.
In the following days, Eve's manipulations intensify. She seeks to solidify her position, but when a note arrives for Karen during a dinner celebration, tensions mount. In the ladies’ room, Eve pleads her case to Karen, claiming that DeWitt has twisted her words, insisting she never meant to harm Margo. Karen, although hesitant, finds herself swayed, particularly when Eve threatens to expose her role in Margo's recent predicament regarding the gas tank.
Soon, Eve lands the lead role in Lloyd's play. As the opening night approaches, she masterfully maneuvers relationships, simultaneously sowing discord among her rivals while maintaining a façade of kindness. With Addison DeWitt guiding her, Eve feels unstoppable, but unbeknownst to her, he has other plans and is aware of her true nature—an ambitious chameleon who has fabricated her identity.
Confronting Eve, DeWitt reveals his understanding of her deceptions, making it clear that he intends to control her career. Despite her initial resistance, Eve realizes the precariousness of her position and ultimately succumbs to DeWitt’s power over her future.
The narrative loops back to the prestigious ceremony, where Eve Harrington stands before her peers, collecting accolades while revealing the lengths she has gone to achieve her ambitions. Cold and isolated, she has sacrificed all meaningful connections for her success. As she returns to her empty hotel room, she encounters a young admirer named Phoebe, who idolizes her—provoking Eve's ire. Just as Eve begins to settle, Addison DeWitt reappears, and through a single knowing glance at Phoebe, he recognizes the cyclical nature of ambition and manipulation, hinting that a new chapter is about to unfold.
