A young boy discovers his grandmother's secret: she was once an international jewel thief known as the "Black Cat". As he devises a plan to raid the Tower of London with her, they must navigate a ballroom dancing competition and evade suspicion from their nosy neighbours. With its unique blend of action, comedy, drama, and family values, Gangsta Granny is a heartwarming tale of an unlikely bond between a boy and his "gangster" granny.