Deadly Duo is a 1962 American mystery film directed by Reginald LeBorg and released by United Artists.
After her auto-racing son is killed in a crash, wealthy Leonora wants custody of her grandson. Her daughter-in-law Sabena absolutely refuses, even when Leonora's attorney, Preston Morgan, approaches her with an offer of $500,000.
Sabena's twin sister, Dara, wants the money, no matter what. She and her accomplice Jay Flagg scheme to push Sabena's car off a cliff, then collect the half-million dollars for themselves. Their plot is foiled, however, and while Leonora sees the error of her ways, Sabena develops a romantic interest in Morgan.