Every parent makes mistakes. But what if you could fix them? Redo the moment? Would you? A psychological thriller that blends scientific speculation with a stunning portrait of the relationship between fathers and sons. Caryl Churchill’s A Number is a powerful, unpredictable and devastating play that delves into the morality of genetic experiments, the essence of paternal love and the debate of nature versus nature. Over multiple meetings Salter reconnects with his sons, grappling over the lies and truths of their shared and uncanny past. With each encounter the sons are radically changed but is the father?