We learn the secret ingredients and shadowy forces behind what creates a hit – be it a song, app or meme – with Derek Thompson, author of new book ‘Hit Makers’. Plus, artist and ad man Graham Fink explains his new exhibition ‘Stone Souls’ and some of his most famous campaigns. And we look at the artists who designed some of music’s best record sleeves with Julius Wiedemann, editor of Taschen’s ‘Art Record Covers’.