Art detectives Bendor Grosvenor and Emma Dabiri travel to the National Museum Cardiff to investigate a badly overpainted Madonna, currently attributed to a follower of Botticelli, that shows signs of being worthy of investigation. Bendor believes the picture is good enough to warrant an attribution to Botticelli's workshop, and conservation may reveal evidence of the hand of the master himself. Cleaning the picture confirms that a faker had tried to artificially age the panel. Bendor then travels to Florence to explore the early Renaissance, and the life and work of Botticelli, hoping to find evidence that will support a new attribution. Meanwhile, Emma Dabiri explores the story of the two immensely wealthy Welsh sisters who donated the work to the museum, and discovers how they tried to bring about their own renaissance in the cultural life of their native Wales.