Teresa Salgueiro has been making solo albums since 2006, but 2012's O Mistério marks a new point of departure for the internationally revered Portuguese singer. All of her previous records were content to present Salgueiro in the role of sublime interpreter and/or musical anthropologist, as she explored the musical heritage of Portuguese, Brazilian, and Italian culture. O Mistério, on the other hand, is the first album of original material credited to her name, and to her notable cast of supporting musicians: Carisa Marcelino (accordion), Óscar Torres (double bass), André Filipe Santos (guitar), and Rui Lobato (drums and percussion); Lobato also co-produces, together with Salgueiro and António Pinheiro da Silva, who had worked with the singer on several Madredeus' albums.