The story, in brief, comes from Greek mythology, and concerns Andromeda, the daughter of Cassiopeia, who has been freed by Perseus from the rock where she has been chained. Cassopeia has promised Andromeda to Perseus as a reward. For her part, Andromeda is grateful, but she initially refuses Perseus because she is in love with Daliso. In time, however, she learns that Daliso is incapable of love, and she willingly accepts Perseus, thereby allowing the serenata to end with rejoicing. It is likely that Andromeda liberata was composed for a happy event, possibly the return of the exiled Cardinal Ottoboni to his native Venice.