Rascar Capac, the sinister creature featured on Hergé's album “The Seven Crystal Balls” (1948), has left its mark on many generations of readers. To draw it, the Belgian cartoonist was probably inspired by a mummy exhibited in the first pre-Columbian exhibition organized by the Brussels Cinquantenaire Museum in 1923. Two intrepid archaeologists embark on a fascinating journey to reconstruct the story of the mysterious mummy.