Simplify the following text for a Grade 7 native English-speaking person.
Original: ... Celeste Aida \/ `` Heavenly Aida '' ) . Aida , who is also secretly in love with Radames , is the captured daughter of the Ethiopian King Amonasro , but her Egyptian captors are unaware of her true identity .
Simplified: One of them is the Ethiopian king , Amonasro , father of Aida , although the Egyptians do not know who he is .