Kensington Gardens, by Rodrigo Fresan (trans Natasha Wimmer)

The centenary of the first performance of Peter Pan has stimulated several books about its author. JM Barrie is someone whom the modern mind finds hard to grasp, a man passionately attracted to playing games with boys. How could he not be a pederast?

There is no evidence at all that he was. Rodrigo Fresan's novel shows how Barrie himself was Peter Pan. Barrie fled reality on to the stage, where he could imagine childhood, that time when gravitas and gravity are abolished - when boys can fly.

Fresan is a well-known writer in Argentina, but this is his first book to be published in English. It is a generous, rambling novel that owes a great deal to the magic-realist tradition, with its interlinked stories, improbable events and exaggerated coincidences. Full of allusions, wordplay and jokes, it must have been a nightmare to translate, and Natasha Wimmer's version is excellent.

In fiction, Fresan is able to delve deeper into Barrie's motives and feelings than in biography. The most beautiful parts are the descriptions of his childhood and desolate but dignified old age.

The death of his better-loved brother when a child and the despair of his mother pushed Barrie into an alternative world of books. Fresan also evokes the "unending fun" of Barrie and the Llewelyn Davies boys capering through Kensington Gardens.

The fun is fleeting, though. Loneliness and death bear down on the novel, which opens with the suicide of Peter Llewelyn Davies at the start of the 1960s. It moves towards the horror of the First World War, when Peter and Barrie's "lost boys" really are lost in the trenches.

Fresan is a brilliant writer, in the sense that he loves the bright roll and the sound of words. Kensington Gardens is a book you will adore for its ingenuity and energy and its zest for language - or hate for its self-indulgence.