Kort efter afslutningen af tredje verdenskrig finder den overlevende Kate en radio, som taler til hende. På stemmens opfordring begiver hun sig afsted til fods for at finde mad og kontakt til andre overlevende.
Australia in the near future. It is the Christmas Eve, eight days after the end of World War III. The country is almost empty, devastated, and cold. There are only few survivors, waiting to die. Sound of sirens is the only noise one could hear. Several people around the globe receive a message from an unknown sender. For Kate (Cara Culligan), the signal is received through an unplugged radio. That brings hope in her desperate heart and she embarks by foot on a mission to find the mysterious broadcaster. The cinematography of the “Black Garden” is decided in a depressing monochromic style. That perfectly matches the apocalyptic topic of the film that is based on Dante’s Inferno - the 9th circle of hell.