In “Happy Mistake,” which is the only song not also in the film, Gaga processes her past through the lens of her character, Lee. Over a haunting guitar arrangement, she sings about wrestling with sadness in the public eye and how desperately she wants to put herself back together and put on a show for fans.

"Sometimes we can go through dark times and feel like happiness is an accident when it happens," she told Kimmel.

Folie à Deux companion album, Harlequin. Lady Gaga Goes Full Harley Quinn with Performance of “Happy Mistake” on Kimmel: Watch Eddie Fu