Once every ten years Granta publishes a list of the twenty best American fiction writers under the age of forty. In 1997 and 2007 we picked out such luminaries as Anthony Doerr, Jeffrey Eugenides, Jonathan Franzen, Nicole Krauss, Lorrie Moore and Yiyun Li. This issue distils the preoccupations of another generation; a selection of fascinating writers you will be hearing more from.