He does tell her that the Cairo underworld refer to the master or Sethos, the person Amelia likes to call the Master Criminal. Sethos is a name related to the ancient Egyptian god Set or Seth, of deserts, disorder and violence, as the Egyptologists of the Emerson household know.
Amelia refers to Sethos as the Master Criminal, who is acknowledged within the Cairo underworld. This name is related to the ancient Egyptian god Set or Seth, known for his association with deserts, disorder, and violence among the Egyptologists at the Emerson household.