Claire Boltwood and her father drive their Gomez-Dep roadster from Minnesota to Seattle, exposing themselves to all the perils of early motoring. They encounter the upper-crust Boltwoods who are at once more noble and more insignificant. Other class barriers exist between Claire and a mechanic named Milt, who, along with his cat, follows close behind.

Free Air anticipates many of the themes of Lewis' later novels and John Steinbeck's Travels with Charley. Claire blazing her own trail West personifies the nineteenth-century pioneer woman and looks ahead to the independent minded 20th century woman like the heroines played by Katherine Hepburn.