Although Thunderball was the fourth installment in the James Bond franchise, it was originally intended to be the very first. Bond creator Ian Fleming collaborated with Jack Whittingham and Kevin McClory on an original story, part of which Fleming later adapted for his novelization. When Harry Saltzman and Albert Broccoli bought the rights, McClory instigated legal action and Thunderball was shelved until 1965.

Once it was actually made, the film boasted the biggest, baddest, and beefiest wallop ever. From jet packs to underwater battle sequences, Thunderball’s budget exceeded that of the first three films combined. Sean Connery returned with Bernard Lee, Lois Maxwell, and Desmond Llewelyn for his fourth adventure. Raquel Welch was actually cast as Bond’s love interest Domino, but the suits at 20th Century Fox had her released from her contract (so that she could join the cast of Fantastic Voyage instead). Eventually, Miss France Claudine Auger was cast as the beautiful apple of Bond’s eye. Like Gerte Fröbe in Goldfinger, Auger’s lines later had to be dubbed because of her poor English. Principle villain Adolfo Celi would also undergo the dub treatment.

The story begins with SPECTRE agent Emile Largo (Celi) forming a plan to hijack two nuclear bombs. While recuperating at a health resort, Bond stumbles onto the plot, which involves a NATO officer who is replaced by a perfect imposter. Once the bombs go missing, Bond’s only hope is to find the sister of the murdered NATO officer in Nassau, where she just happens to be Largo’s mistress. The cat and mouse continues as SPECTRE holds the world for ransom while Bond searches desperately for the bombs.

The film continued the newfound “spymania” sensation begun by its predecessor Goldfinger. The very first James Bond action figures and Thunderball board games hit the market. The film brought home the very first on only Special Effects Oscar for the franchise.

After its release, McClory would continue his legal battle for the rights to Thunderball which would climax with his own adaptation: a 1983 renegade version called Never Say Never Again, also starring Connery with Kim Basinger, Barbara Carrera, and Max Von Sydow. But its paltry box office was laughable compared to Thunderball, which remains the top grossing Bond film of all time by almost twice as much as any other. Audiences weren’t alone in their favor: not only did Connery prefer Thunderball, he considered it his favorite of all his performances.