There’s a good collection of familiar actors involved, but the narrative feels underdeveloped. "Frank McNally," portrayed by Trevor Howard, manages to outwit Interpol's attempts to apprehend him, seemingly making their work look foolish. He doesn't truly encounter an equal until he murders the sister of US agent "Sturgis" (Victor Mature). This new adversary proves far more resolute and immediately focuses on “Gina” (Anita Ekberg), a key figure in the operation, following her across Europe before ultimately zeroing in on his target as “McNally” prepares for a large-scale scheme in New York. The narrative structure resembles a travelogue, which does contribute to a certain speed but results in excessive time spent on planes, in airports, and sightseeing instead of fleshing out the characters or deepening the plot. Neither Mature nor Howard deliver particularly compelling performances; Ekberg is almost entirely silent until near the film’s conclusion, while Bonar Colleano as "Amalio," a grifter, provides the most memorable contribution, appearing more skilled at tracking “McNally” than his police partner. The resolution feels underwhelming—more of an illustration of how well global policing and communication work than a satisfying culmination to a thriller—and I felt it simply didn't have enough impact.

Source on TMDB