In Biggles Takes a Hand, Anna Lowenhardt was the daughter of Max Lowenhardt and a friend of the family of Oberst Hans Roth. She was engaged to Moritz Roth, son of the Oberst. At the time of the events in the book, Anna was a pretty girl of about seventeen. Anna worked for a year in London as a governess to some children
Some three years before the events in the book, Anna had finished school. Her father decided she should learn English and sent her to London. There she lived at Westwinds in Hampstead, the residence of Dr Bruno Jacobs, a German emigre dentist and friend of Max Lowenhardt. At Westwinds, Anna found work as a governess, looking after the children of a widowed relative of Dr Jacobs who was living with him and his wife. After working for a year, Anna returned to live with her father in West Berlin.
Biggles first met Anna when he went to the home of Max Lowenhardt at Antonstrasse, No 71, West Berlin, hoping to get from Lowenhardt some means of tracing the whereabouts of his friends the the Roth family. Finding Anna reluctant to say much and the Professor out, Biggles asked Anna to pass him a message that the Roths could be in danger and he needed to find them as soon as possible. Instead of passing the message, Anna decided to travel to London by the next flight, leaving a note for her father.
Biggles next met Anna at the airport in West Berlin, both having bought tickets for the same flight. When Biggles noticed that some men were following her, he decided to intervene and sent a message ahead to ask Algy to meet him and Anna at London Airport while arranging with customs to delay the agents who were following her.
This convinced Anna to cooperate with Biggles. She revealed that Oberst Hans Roth had been arrested and executed by the East German government but Frau Roth and her two children managed to escape to West Berlin. They stayed with Max Lowenhardt and Anna but as they would probably be safer in London, Anna gave them a letter of introduction to Dr Bruno Jacobs and they left for Britain a day later.
Unknown to Anna and the Roths, a gang of professional killers led by Ludwig Karkoff was later sent to hunt down the Roths in London. Anna could also be in danger and so Biggles needed a place for her to stay while they dealt with the gang. Dr Jacobs had sold his house at Hampstead but Biggles later learnt that he had moved to Saxton Old Hall in Surrey. Accordingly he arranged for Ginger to take her there. Unfortunately, Anna disobeyed instructions. Instead of waiting to be picked up from her hotel, she walked over to Biggles' apartment at Mount Street which was under surveillance by two gang members. Biggles was forced to improvise a counter-surveillance drill to misdirect the gang's surveillance and allow Ginger and Anna to have a clear run to Surrey. At Saxton Old Hall, Anna was later joined by her father who had traveled to London after reading Anna's note. He had also found Dr Jacob's new address and made the journey to Saxton. There they remained safe until the gang was neutralized.
At the end of the story, it was stated that Anna emigrated to the United States with her father and thereafter she married Moritz Roth.