Jennifer and Alison go back years, first meeting when teenagers at school. Their friendship has seen its ups, downs, highs, lows, triumphs, and disasters.

The friends are now in their late forties. Alison is happily married to the dull but dependable Malcolm, and they have a teenage son. Jennifer is divorced, well-off, and carefree, and determined to stay that way.

So she astonishes everyone when she announces she is pregnant. Shock turns to delight, and Alison is keen to support her oldest friend. But when she finds out who the father of the baby is, the friendship must face its biggest test.