As a young girl, Princess Dala received an extraordinary gift from her father, the Shah of Lugash: the Pink Panther, a magnificent diamond known for its remarkable size and an unusual flaw that resembles a leaping panther when observed closely. However, after the tragic demise of her father and the subsequent military coup in her homeland, Dala finds herself exiled. The new regime claims ownership of the Pink Panther, seeking to have the World Court decide its fate, but Dala steadfastly refuses to part with her cherished gem.
Meanwhile, the notorious jewel thief known as the Phantom has made headlines again, having successfully stolen half a million dollars' worth of jewels in Rome. In Paris, the bumbling but determined policeman, Inspector Jacques Clouseau, is tasked with capturing the elusive Phantom. Unbeknownst to Clouseau, the Phantom is intricately linked to his wife, Simone, who assists in the thefts while simultaneously benefiting from her husband’s obliviousness.
As events unfold, Dala (played by Claudia Cardinale) finds herself vacationing at a luxurious ski resort in Cortina D'Ampezzo, unaware that the suave English playboy Sir Charles Lytton, who lives a double life as the Phantom, has set his sights on her prized diamond, which is insured for a staggering $0.5 million. Also present is Charles’ nephew, George, who hopes to embezzle the diamond and frame his uncle in the process. Posing as a recent college graduate preparing for the Peace Corps, George aims to maintain the facade of his lavish lifestyle, which is at odds with his significant debts.
To gain Dala's trust, Charles orchestrates the kidnapping of her dog, thus appearing as a hero when he offers to rescue it. His charm gradually wins Dala over, leading her to indulge in luxuries that conflict with her principles, such as drinking Champagne. As romance blossoms between them, Charles' plan grows increasingly complicated when he learns that George is also at the resort, leading to a series of mishaps that reveal the tangled web of deception.
Simultaneously, Clouseau, in his signature clumsy fashion, is hot on the trail of the Phantom, obliviously thwarting potential thefts while inadvertently digging deeper into the intrigue. Simone tries to manage her affair with Charles while preventing George from complicating matters further. The night before their departure, George discovers his uncle's true identity, and the stakes rise as Dala prepares for a gala that she suspects will be the scene of the Pink Panther’s theft.
At the fancy-dress party, Charles and George attempt to steal the diamond but find themselves thwarted when they realize it has already gone missing. Their escapade ends in a chaotic car chase that culminates with their capture after a series of unfortunate accidents.
As tensions escalate, Simone approaches Dala, who reveals that she has taken the diamond herself to avoid being sent back to Lugash. During the trial, Clouseau's unexpected testimony leads to a moment of revelation; his clumsiness inadvertently reveals the jewel he had hidden away, leading to his unconscious state from shock.
In a surprising twist, Clouseau becomes the center of admiration from an audience of young women, while a regretful Simone fears for his fate. Sir Charles reassures her that when the Phantom strikes again, Clouseau will be vindicated. As they drive away to continue their life of crime, Princess Dala departs to her homeland, leaving a wave of chaos in her wake, and Clouseau, despite his circumstances, reflects, “Well, you know... it wasn't easy,” as the Pink Panther finds himself in yet another comic misfortune.
