In his brilliantly provocative, entertaining and utterly infuriating postmodern manifesto Reality Hunger, published in 2010 to much acclaim and derision, the novelist and writer David Shields made a case for books that mixed things up, blurred boundaries and generally tossed stuff together into a fragrant potpourri of fact, fiction, gossip, rumour and anecdote. Salinger is the offspring of the Shields shake-it-up method – a 700-page mugwort-and-jujube mash-up of biography, critical summary and cuttings file. Compiled by Shields with the film director Shane Salerno, and based on their recently released documentary film, Salinger is not really a book. It’s a scrapbook. Or maybe just a scrappy book. Or a book intended to start scraps: Shields certainly strikes one as a slugger. Who knows? Whatever it is, it’s like no biography you’ve read before.

Shields and Salerno set out to answer three simple questions: why did Salinger stop publishing after the massive success of The Catcher in the Rye (1951) and a handful of short stories; why he went to live in seclusion in Cornish, New Hampshire; and how exactly he spent the last