The lady in question is Adele Bloch-Bauer who was the subject of a magnificent painting, deploying lots of gold, by the Austrian artist Gustav Klimt. Following the Anschuss of 1938 when Germany took over Austria, this painting was one of many, many artefacts seized by the Nazis from Jewish families in occupied Europe.
The film tells the story - a little fictionalised - of Adele's niece Maria Altmann who escaped from Vienna to live in California and, during the 1980s as an octogenarian, pursued an audacious claim to take back this painting and other Klimt works from the Austrian Government. Helen Mirren is brilliant as Altmann in another distinguished performance in a sparkling career during which she has played everything from "The Queen" to an assassin (RED"), while Ryan Reynolds is surprisingly good as her lawyer Randy Schoenberg in a role a million miles from "Green Lantern" or "Deadpool".
There's a lot going on in this film: legal battles over the art work with some classic courtroom scenes, flashbacks (in sepia colours) to Altmann's earlier life in 1930s Vienna, and an evolving relationship between the irascible Altmann and the idealistic Schoenberg, both descendants of famous Austrians. This is not the kind of film that was ever going to be a major box office draw but it is certainly worth a home viewing.
