"Abigail's Song" was a song that Abigail Pettigrew once sang at the Eleventh Doctor's insistence. Because of the perfection of her voice, she was able to use the melody to resonate the fog crystals in the skies above Sardicktown. This, in turn, unlocked the clouds, created snow and allowed an endangered spaceship — carrying a honeymooning Amy Pond and Rory Williams — to land safely on the planet. (TV: A Christmas Carol)