Tailspin by Sandra Brown
Rye Mallett, a fearless "freight dog" pilot charged with flying cargo to far-flung locations, is often rough-spoken, usually unshaven, and he never gets the regulation eight hours of shut-eye before a flight; but he does have a rock-solid reputation: he will fly in the foulest weather, day or night, and deliver the goods safely to their destination. So, when Rye is asked to fly into a completely fogbound Northern Georgia town and deliver a mysterious black box to a Dr. Lambert, he doesn't ask why--he just ups his price.
As Rye's plane nears the isolated landing strip, more trouble than inclement weather awaits him. He is greeted first by a sabotage attempt that causes him to crash land, and then by Dr. Brynn O'Neal, who claims she was sent for the box in Dr. Lambert's stead. Despite Rye's "no-involvement" policy when it comes other people's problems, he finds himself irresistibly drawn to the intrigue surrounding his cargo...and to the mysterious and attractive Brynn O'Neal.
Soon Rye and Brynn are in a treacherous 48-hour race to deliver the box before time runs out. With the hours slipping by and everyone from law enforcement officials to hired thugs hot on their heels, the two must protect their valuable cargo from those who would kill for it--that is, if they can trust each other.