Research into the role of fiction in engaging people with science is a growing area, but a little studied medium in this respect is "popular theatre," or non-pedagogic theatre that exists primarily as a work of art. This study investigated audience engagement with human cloning issues after seeing a performance of Caryl Churchill's 2002 cloning-themed play, A Number, and compared this to the level and quality of engagement shown by people who participated in a group discussion about human cloning. The play prompted a majority of audience members to be engaged with human cloning, markedly increased the salience of the issue for its audience, and brought to light new perspectives on it for them. The proportion of people who reported thinking about human cloning two months after the play was quantitatively similar to those who took part in a group discussion, but the conversations that resulted from each stimulus were qualitatively different, with the play providing a concrete case study that grounded discussion. The unique contributions that popular theatre can offer science communication are discussed.