Lyric Theatre performers in the musical comedy Once Upon A Mattress - April 4-6, 2025. Music by Mary Rodgers, lyrics by Marshall Barer. Once Upon a Mattress is a musical that offers a twist on the classic fairy tale, The Princess and the Pea. The story is set in a medieval kingdom and follows the search for a princess to marry Prince Dauntless, a young man whose domineering mother, Queen Aggravain, has made it nearly impossible for anyone to pass her rigorous tests.