The Missing Treaty () is a 1933 Italian mystery film directed by Mario Bonnard and starring Ernesto Sabbatini, Leda Gloria and Mino Doro. It was shot at the Cines Studios in Rome. The film's sets were designed by the art director Gastone Medin. A separate French version Le masque qui tombe was also produced.
A document containing information about a new secret weapon is stolen from the safe in an admiral's house. Inspector Brown of the police is called in to investigate.