Nick Marshall (Mel Gibson), a Chicago ad executive, and alpha male, who grew up with his Las Vegas showgirl mother, is a chauvinist. He is skilled at selling to men and seducing women (such as local coffee attendant Lola (Marisa Tomei). However, just as he thinks he's headed for a promotion, his manager Dan (Alan Alda) informs him that is hiring the talents of Darcy McGuire (Helen Hunt) instead, to broaden the firm's appeal to women.
Also, his estranged 15-year-old daughter Alex (Ashley Johnson) is spending two weeks with him while his ex-wife Gigi (Lauren Holly) goes on honeymoon with her new husband. Alex is embarrassed by Nick, and resents him being protective when she brings her boyfriend home.
Needing to prove himself to Darcy and Dan, Nick attempts to think of copy for a series of feminine products that Darcy gave out. However he slips and falls into his bathtub while holding an electric hairdryer, electrocuting himself. The next day, Nick wakes up able to understand his maid`s thoughts as she cleans his apartment. As he walks through a park and encounters numerous women he hears their innermost thoughts, even those of a female poodle. This proves to be an epiphany for him when he hears the thoughts of his female co-workers (some of whom have slept with him and regretted it). When he goes to a previous therapist (Bette Midler) (who also disliked him), she realizes his gift: "If Men are from Mars and Women are from Venus, and you can speak Venusian, the world can be yours."
Nick eavesdrops on women's thoughts and uses their ideas as his own, but also develops real friendships with his co-workers. But as he spends more time with Darcy, he is attracted to her. However when he tries to get closer to his daughter, she resents him for trying after so many years of neglect. Nick shrewdly suspects her older boyfriend plans to sleep with her and then dump her, but she does not want his advice.
Nick and Darcy begin to spend more time together, and ultimately kiss. When he manages to trump Darcy out of her idea for a newNike ad campaign aimed at women, he regrets his selfishness, especially as it leads to her being fired.Nick loses his gift during a storm while looking for an assistant named Erin (Judy Greer) whom he overheard planning suicide. He is also reconciled with his daughter when her boyfriend rejects her. Nick finally visits Darcy and explains everything. She regains her job and fires Nick. But she forgives him, and agrees to save him from himself, to which he responds "My hero".