Nápev was a little girl whose father was killed in riots in Prague when she was five. Her most valued possession was a copy of Czech Folk Tales, which her father used to read to her every night.
After his death, she used energy from the sun and the electricity of Prague to bring the folk tale characters to life. The energy drain caused the city to suffer blackouts and power surges. The Seventh Doctor and Ace convinced her to stop, and the Doctor brought her to Gallifrey. (PROSE: Fable Fusion)