Aircraft plant worker Robert Cummings is accused of sabotaging his factory and causing the death of a co-worker. Actually, Cummings is the fall guy for a clever ring of Nazi spies, headed by above-suspicion American philanthropist Otto Kruger.
Our hero goes on a cross-country chase after genuine saboteur Norman Lloyd, all the while pursued himself by the police.
Along the way, he acquires a reluctant travelling companion in the form of Priscilla Lane, who at first despises Cummings and intends to turn him over to the authorities at the first opportunity, but who gradually comes to realize that the boy is innocent.
Alfred Hitchcock intended Saboteur to be the American equivalent to his British The 39 Steps, employing such details as the solid-citizen villain, the handcuffed hero, the unwilling blonde heroine, and any number of stopovers with a variety of offbeat characters (a travelling freak show, a compassionate blind man, a grizzled old prospector who turns out to be one of the spies, etc.)