One of Bergman's darkest films, and the first of a thematic trilogy exploring the question of the existence of God, Through A Glass Darkly depicts a young woman's descent into madness. The film is set at an isolated house on the coast and focuses on four characters: David, a writer, his adult children Karin and Minus, and his friend Martin - who is married to Karin. The idyll of the opening is quickly shattered as the tensions in their relationships and the extent of Karin's mental illness become more and more apparent. Bergman was not entirely happy with this film, and it has its imperfections, but it is more than redeemed by the performance of Harriet Andersson as Karin, which is the most stunning and powerful piece of acting I have ever seen on film.