Lexi, sixty-three and recently widowed, is facing the inevitable vicissitudes of life. After passing through a phase of numb immobility, Lexi makes a half-hearted attempt to meet some older men, but the experiences are disappointing.

Undaunted, Lexi begins to accept the idea of being alone. Then circumstances disrupt her quiet routine - in the form of two house guests. In the physics of relationships, Lexi observes that nature abhors a vacuum. But she wonders if she herself has manipulated her circumstances to fill that vacuum. Eventually, Lexi encourages both house guests to move on. Ironically, her unselfish kindness leaves her once again alone.

Through some strange physics of attraction and repulsion, however, her ex-husband reappears. Is he a changed man ... or just acting like one? In the end, Lexi learns how to come to terms with her solitude, to resist entropy, and to fill the vacuum in her own way.