Low-budget but suspenseful Cold War yarn, with Sterling Hayden & Ruth Roman. Hayden is gruff John Emmett, whose car breaks down in California on his road to nowhere (supposedly en route to visit his folks in Texas). The suspiciously friendly Ann Nicholson (Roman) offers Emmett a lift, as long as he'll drive some. She's going to New Mexico.
Along the way, her psychiatrist (the future Col. Klink, Werner Klemperer) & his nurse pop up; with sundry likewise suspicious characters: cops, a university dean, CIA, FBI (Ken "Festus" Curtis), & hired killers. Ann's carrying missile secrets, which are carved into a ladies' mirror. There's a fine sudden twist to the showdown with the guy for whom the missile secrets are meant.
For a low-budget thriller, the acting's surprisingly low-key. Hayden does restrained bewilderment very well: quite contrary to his lead role in "The Killing," a couple years before. Roman is also restrained in her role as a suspected spy, with secrets of her own culled from both sides of the globe. As our Dad used to say, "A goody to see again!"