Porfirio Rubirosa was a man of many parts, part time diplomat, part time polo player, part time race car driver, and most definitely full time lover. He's the man on which lead Bekim Fehmiu's part is based. In that lies the tale of The Adventurers.
Harold Robbins up to this point had done reasonably well on the screen with successful adaptions of novels like The Carpetbaggers, Where Love Has Gone, King Creole, etc. But Paramount spent a fortune on this film with a few name players in supporting roles, but came up real short with Yugoslavian actor Bekim Fehmiu in the lead. Sometimes casting an unknown works, the best examples being Peter O'Toole in Lawrence Of Arabia and Errol Flynn in Captain Blood. But here the distinctly uncharismatic Fehmiu just had no chemistry with any of the women he was to wed and/or bed. When you're basing the lead character on a notorious lover of the flesh, that's kind of essential.
Rubirosa in real life had an on again off again relationship with Rafael Trujillo dictator of his native Dominican Republic. Alan Badel plays the Trujillo figure who did not come to as glorious an end as he does here. Badel was certainly as treacherous as Trujillo in real life.
Rubirosa was married 5 times in real life and one of those wives was Barbara Hutton who got around herself pretty good as another of her husbands was Cary Grant. Here her role is played by Candice Bergen who likes a good time, but also wants a family.
The girl from Fehmiu's mythical country of Corteguay is Leigh Taylor-Young. Anna Moffo stands in for fellow opera singer Maria Callas. You'll recognize a few other players on the international scene.
The climax is the revolution against the duplicitous Badel and the battle scenes are staged well, a lot of the film's budget certainly went there.
As for Bekim Fehmiu international stardom was not to be, but it looks like he had a respectable career in his native Yugoslavia.
If you like to stargaze and note some of the names that are present in the cast or if you are devoted to the novels of Harold Robbins then I would recommend The Adventurers. Otherwise it's pretty mediocre.