Tom and Gerri are a couple who are drifting past middle age into their sixties; he's a geologist and she's a psychotherapist. Tom and Gerri have a stable and happy marriage and a grown son, Joe, an activist lawyer who hasn't settled down yet, much to his mother's chagrin. One of Gerri's co-workers and close friends is Mary, who puts up a façade of desperate good cheer despite the fact she's been very lonely since her husband left her and has been drowning her anxieties in wine. Gerri has unsuccessfully tried to fix Mary up with Tom's sloppy but good natured pal Ken, and she's startled when Mary begins openly flirting with Joe, more than 20 years her junior. Mary's troubles only grow worse when she stops by Tom and Gerri's place only to be introduced to Katie, Joe's new girlfriend.