Millie McCall is an exuberant, Harley-riding character who hosts scandalous poker parties for the local fellows wearing her red negligee. Young Jim Halprin is a stand-in at the party, forewarned to flee the moment the last card slaps the table. A swaggering Harley rider himself, Jim bonds with Mrs. McCall instead, as she absorbs lunar energy, shedding her disheveled appearance, becoming a tantalizing beauty. Jim rescues Millie's flashy Harley from destruction by juvenile predators but Millie laughs off the pranksters and leads Jim off on a wild chase in the wrong direction over the twisting roads of Orcas, the most rugged and dangerous of the San Juan Islands. Millie is evading her keepers and tormenting her husband, or so Jim soon learns. He finds himself on a mad ride on the night of the full moon, terrified to learn that Mrs. McCall's freedom ride is meant to last forever.