The Serpent's Egg (1977) is a relatively minor piece in Bergman's classic canon, this may have been due to the conditions of its production- Bergman having tax problems with the Swedish authorities and like many European auteurs (Wenders, Herzog, Kieslowski) made this film outside of his own country.
The film is set in pre-World War II/Weimar Berlin (the films was actually co-production between Germany and the US) and is set around a circus- recalling two later films influenced by Bergman: Woody Allen's Shadows & Fog and Wim Wenders's Wings of Desire/Sky Over Berlin.
The setting and themes have also been repeated subsequently, perhaps as retribution and comprehension of the Third Reich- this followed Cabaret and the exploitative Salon Kitty, but also fits in the same thematic/historical contiuum as films like The Marriage of Maria Braun,Mephisto, Invincible and Faraway, So Close!.
However, this is far from Bergman's most coherent work- lapsing into nastiness as perhaps he had only done previously on The Hour of the Wolf. David Carradine is miscast, though Bergman regular Liv Ullmann is present. As ever, the photography by Sven Nkyvist is brilliant- reason alone to buy this film.
The Serpent's Egg is good value at this budget price, I would be more reticent buying it if it were conventionally art-housed price (£15 plus). It is rarely seen and an oddity in Bergman's canon as films like Torment (which he didn't direct) or The Hour of the Wolf. This is far from his best work of the 1970's, Scenes of a Marriage- which is a much sounder purchase if you haven't seen it.