Late September takes place over a 24-hour period, in a beautiful Kent house and garden, and follows the course and aftermath of a birthday celebration organised by a middle-aged woman for her husband to whom she has been married for nearly 40 years. As the day and night progress, old rifts, new relationships and secrets emerge amongst friends, and the underlying tensions in the marriage can no longer be contained. This age group, the post war generation now approaching old age, has not received so much attention in film and the problems these friends face are specific but universal and recognisable to us all; their lives, their hopes and fears for the future are portrayed with a total lack of sentimentality but also with great warmth, humour and empathy.