By decoding ancient hieroglyphic texts, Jean-François Champollion gave voice to an enigmatic civilization, but behind his legendary feat is a mysterious brother who made it possible. The recent discovery of correspondence between Jean-François Champollion and his brother Jacques-Joseph now allows us to fully understand how a young, self-taught genius was able to make one of the most important discoveries of the 19th century. Without the ingenuity and unfailing support of his older brother, Jean-François would never have succeeded in solving this enigma, which had international repercussions. With animated sequences of their private correspondence, and with the help of archives and expert analysis, this film revisits this unique scientific, human and intellectual adventure to celebrate the bicentenary of the decoding of hieroglyphics.