Iolanthe is a Gilbert & Sullivan operetta about a fairy who married a mortal leading to her banishment and the birth of her her half-mortal son, Strephon.  When Stephen wishes to marry Phyllis, a ward of the court, the Lord Chancellor (who also has designs on Phyllis) forbids it.  To complicate matters, the entire House of Lords is also courting Phyllis, and have no idea that Strephon is in fact the son of the Lord Chancellor himself and his banished fairy wife.  The fairies intervene, leading to a show down between the immortal fairies and the ridiculous mortal peers.