The song "Dr. Jekyll and Mr. Hyde" tells the story of Dr. Jekyll, a man who becomes obsessed with knowledge and begins experimenting on himself. He ends up drinking a dangerous chemical mixture that transforms him into the evil Mr. Hyde. The lyrics describe how Jekyll's appearance and personality change, and he becomes a murderous and sinister figure in the foggy streets of London. The song is a cautionary tale about the dangers of unchecked ambition and the dark consequences of tampering with nature. It serves as a warning to listeners about the potential for evil that lies within us all, and the importance of self-control and understanding our own inner demons.