The Last of the Secret Agents?

Two American tourists, Marty Johnson and Steve Donovan, stumble into an international art theft ring, THEM, led by the cunning Zolten Schubach. Forced to work for GGI, their adversaries, they're equipped with The Umbrella, a rejected spy gadget. As they mingle with THEM at a chateau, they discover a plan to steal the Venus di Milo at the London World's Fair. Using The Umbrella, they alert GGI and are tasked with infiltrating the gang. Chaos ensues on a Paris-bound train and in a helicopter chase to stop the thieves. After capturing the thieves, Marty and Steve return home as heroes, but their victory is short-lived as the Statue of Liberty is suddenly removed from its foundation.