In the film, a young man wins a small fortune through gambling according to the advice of an archaeologist's ghost.

While investigating the archaeologist's supposed suicide, the man and his friend discover a Jewish underground city beneath Habsburg Madrid.

They discover a passage from Mantua's home into an underground city under Habsburg Madrid, founded by Jews escaping their 1492 expulsion and now inhabited by money-forging hunchbacks led by Dr. Sabatino.

Basilio manages to escape and returns with the police to find Inés at her home, who barely remembers what happened.

The film features antisemitic tropes as core element of the plot, namely the appearance of a subterranean city dwelled by nefarious hunchbacks, founded by Jews back in 1492.