She is the daughter of the children's book author Paul Maar and the family therapist Nele Maar and the granddaughter of the actor and theater director Oskar Ballhaus and his first wife, the actress Lena Hutter (1911–2003), who both founded the "Fränkisches Theater" in Coburg in 1946.
After graduating from high school, Maar began working as a museum guard and wrote several screenplays together with Andreas Fröhlich, including for the children's series Siebenstein.
Her picture books tend to be fantastic, the longer stories realistic and often deal with the theme of friendship - between girls and boys, between children and adults and between children and animals.
After the death of her grandmother Lena Hutter, she took over from her and her second husband Herbert Heinz (1922–2002) took over the management of the "Fränkisches Theater", continuing the tradition of her grandparents.
She wrote the play Die Weiße Rose with Andreas Armand Aelter, which was successfully performed at the "Fränkisches Theater Schloss Maßbach", in 2010 the children's play Luzi und die Tanten together with Christian Schidlowsky, which was premiered in Fürth in a co-production between the Fränkisches Theater and the Stadttheater Fürth.