If They Ask for a Hand, Only Give Them a Finger by Peter E. Abresch

When a public garage locked up Chance Dugan's car for the night, with his wallet locked inside the car, he met the lovely Natti Moon who offered to put him up for the night. What's not to like? Except it turned into a week from hell, with both Chance and Natti on the lam from competing government agencies who are out to do them in. And when one got around to asking Chance for a hand, he only gave them a finger.