Strange little movie--tonal shifts abound, such that I was never quite sure what I was watching, but with flashes of brilliance throughout. Jean Arthur is wonderful and heartbreaking as an unwitting interloper in an Andean airline, where pilots are required to undertake death-defying mail runs through the mountain pass. This sets up a love story, a thriller, a drama, and more. The movie suffered, for me, when I tried to place it within a genre--instead, it worked better when I let go of convention and appreciated the opportunity to spend time with these characters in this place. Arthur is the standout, but unfortunately gets forgotten about during the middle third of the movie. Thomas Mitchell and Richard Barthelmess round out a great supporting cast. Am I the only one who thinks Cary Grant was miscast?