Eisenstein And Calavera

The film is based on S. Eisenstein’s film “¡Que viva México!”, short story Maguey. Eisenstein is watching the film footage. Unexpectedly, his film character turns into a revived Calavera and steals his film. Eisenstein pursuits her and finds himself in an episode of his film. Calavera is nearby, she tries to destroy his movie.What is the mysterious film hiding and why does Calavera need it?