A NATO aerial observer, portrayed by actor Paul Stassino, who is murdered by SPECTRE in Thunderball. Referred to as “Commandant” despite his rank of major, he’s assigned to a nuclear bomber squadron based in rural England. Derval is seduced by SPECTRE assassin Fiona Volpe (Luciana Paluzzi) and murdered by Angelo Palazzi (also Stassino), a mercenary who, thanks to plastic surgery, is now an exact duplicate of Derval.
James Bond (Sean Connery) discovers Derval’s body at the Shrublands health clinic. This clue leads him to Nassau in the Bahamas and to Derval’s sister, Dominque “Domino” Derval (Claudine Auger), who happens to be the mistress of the mysterious Emilio Largo (Adolfo Celi), a multimillionaire and SPECTRE spymaster.
Swimming to a downed NATO bomber that has been hijacked to the Bahamas by Palazzi, Bond finds the doppelganger’s body in the plane’s cockpit, where he drowned when Largo cut his air hose. Among his effects, Bond finds Derval’s identification disk and watch—clues that finally convince Domino that Largo is her enemy.