The Driver's Seat
by Muriel Spark
Lise is thin, neither good-looking nor bad-looking. One day she walks out of her office, acquires a gaudy new outfit, adopts a girlier tone of voice, and heads to the airport to fly south. On the plane she takes a seat between two men. One is delighted with her company, the other is deeply perturbed. So begins an unnerving journey into the darker recesses of human nature.