The fourth James Bond film Thunderball had a budget equal to three previous films put together. And it shows. A significant portion of the movie was filmed underwater, including the climatic battle at the end. Connery appears most at ease in the role this time around, as if he could play the character in his sleep. An extravaganza making a move away from the espionage intrigue of the previous three in favor what could be considered an early blockbuster.
The cold open is fierce and violent with 007 getting into a fight with a SPECTRE operative and escaping by way of a jet pack. The main plot involves the sinister SPECTRE organization stealing two nuclear weapons to extort the British government. Bond and all the 007 agents are called into action to retrieve the bombs. Bond has a lead in the Bahamas, where most of the film's action takes place.
Thunderball reveals a little more about SPECTRE. We see one of their meeting at the beginning, a sort of corporation dedicated to disrupting the world. Their leader Blofeld is brutal and will execute anyone on the spot who displeases him - famously parodied in the Austin Powers movies. But the main villain here is Emilio Largo played by Italian actor Adolfo Celi, an eye patch wearing goon who hatches the extortion ploy. Largo managed to set up a double to impersonate a NATO officer to deliver the nukes (in villain fashion Largo immediately dispatches him once the mission is accomplished.)
But Bond learns the pilot's sister Domino (Claudine Auger) happens to be Largo's mistress. Once in the Bahamas Bond romances Domino and manages to infiltrate Largo's plot. While Bond seems to have an easier time than usual this time, even spouting off one liners at will, there's also a nice pace to the film. The rituals of a Bond movie are all here: a meeting M, flirting with Miss Moneypenny, Q supplies gadgets, and some help from Bond's CIA friend Felix Leiter.
Thunderball is doubt an entertaining film and one that improves with multiple viewings. It was also the most violent one up to this point, with an array of sphere guns and sharks. Water sports also play a key role with lots of scuba diving and boating sequences. Part of the appeal of every Bond film, even a saving grace for the lesser ones, is how they always serve as travelogues. The theme song sung by Tom Jones and score from John Barry are both memorable as well, kicking the franchise going at high gear.