Who is hiding behind the mask? At a glamorous masked ball in the opera, a valuable jewel-encrusted necklace is stolen – along with the lapdog of a famous fashion designer. The three !!! immediately start their investigation. Read the thrilling detective story over 24 days – and solve a tricky riddle each day that leads to the next door. Gradually, the investigation wall fills up, bringing you one step closer to the thief. An Advent calendar full of excitement, puzzle fun, and 24 detective surprises – for children aged 8 and up! Contents: Exciting detective story with 24 riddles and 24 great Die drei !!!-gimmicks.