The film opens with a man planting an explosive device in a vehicle across the border in Mexico. Following its detonation on the American side, which results in the deaths of those inside, "Capt. Quinlan" (Orson Welles) begins a somewhat superficial inquiry alongside his counterpart, "Vargas" (Charlton Heston). During their investigation, "Susan Vargas" (Janet Leigh) is drawn into a meeting with "Uncle Joe" (Akim Tamiroff), revealing that her spouse is involved in a familial conflict placing everyone at risk—a realization he quickly confirms when he escapes an attack involving acid. “Quinlan” and his associate “Menzies” (Joseph Calleia) have distinctive methods; Quinlan uses sheer presence to exert influence, keeping the District Attorney under his thumb. However, as this investigation expands, the initial crime becomes less important as "Susan" finds herself isolated in a motel outside of town and potentially faces a horrific drug-related crime that exposes the underlying criminal activity and connects various story elements. The five main characters are portrayed effectively by the actors involved—the narrative progresses with a dark tone, providing considerable engagement, occasional misleading clues, and notably, Welles delivers a compelling performance as an increasingly unpleasant police officer. I initially had reservations about Heston’s casting as a Mexican lawman, but he performs admirably in one of his stronger roles (particularly when not wearing leather), and Janet Leigh, as always, conveys everything with seeming ease. The conclusion blends fear with violence, raising the question of whether the truth will ultimately be revealed; this is definitely something best experienced on a large screen to fully appreciate the impact of the final twenty minutes.

Source on TMDB