Lucille, performed by Paul McCartney, is a cover of an iconic rock and roll song originally by Little Richard. The song is about a man expressing his emotional turmoil and pleading with Lucille, a woman who has left him. The key themes revolve around heartache, desperation, and longing for a lost love. Crucial moments in the song include the repetitive calling of Lucille's name, which underscores the depth of the singer's yearning and the pain of betrayal.