The year 1876 was the pivot of Arthur Rimbaud's life, the midpoint between his intellectual beginning as a child wonder in classical languages and his death in 1891, at the age of thirty-seven. Five years before, the visionary verse of the adolescent Rimbaud had astounded literary Paris, which made him its difficult darling; five years later he was a commercial agent in the remote outpost of Harar, Abyssinia, dealing in gold, ivory, and guns, having abandoned literature completely.

In 1873, after the disastrous conclusion of a demented love affair with an older man, the poet Paul Verlaine, Rimbaud embarked on a restless period of foreign travel, which reached its most distant point in the island of Java. In May 1876 Rimbaud enlisted as a mercenary in the Dutch Colonial Army and sailed to the Indies. Soon after he arrived at his garrison in central Java he deserted and vanished into the jungle. Nothing is known of his whereabouts from then until he turned up again in France at the end of the year.

This book is a study of Rimbaud's journey to Java. I have called it his 'lost voyage' because we know less about it than any other major passage in his life. From the age of fifteen Rimbaud was a great letter-writer, his correspondence occupying hundreds of pages in his collected works; yet not one letter from 1876 survives. By then he habitually concealed his previous life as a poet from strangers, so to the other men in his battalion he was simply young Rimbaud from Charleville, in the Ardennes, clever and good-looking but nobody special. None of his comrades published a memoir about him. Apart from a handful of terse, opaque official documents relating to his enlistment and desertion, the Java voyage is a void. It remains one of the most elusive enigmas among the many that constitute his tumultuous life, and is often overlooked outside Rimbaldian circles.

There are thousands of people (we know who we are) who would take a lively interest if a pair of socks turned up in an old chest in Harar that could be proved to have belonged to Arthur Rimbaud. For them, for us, an attempt to arrive as close as documentary resources permit at an understanding of Rimbaud's adventure in Java requires no justification. Few poets in any language have attracted so passionate a worldwide following - in the derisive vernacular, a cult. When a previously unknown photograph of Rimbaud in Aden came to light in 2010, bringing the number of authenticated images of him as an adult to three, it was a major international news story.

The fascination begins in his beautiful, sometimes bewildering poetry, written before he turned twenty. Rimbaud is one of those writers who can change the reader's life - not in the sense of being an inspiration or a moral guide but by changing the way one thinks. In A Season in Hell, Rimbaud described his growth as a poet:

Poetic antiques played a large part in my alchemy of the word. I became accustomed to pure hallucination: I saw very clearly a mosque in the place of a factory, a school of drummers led by angels, carriages on the highways of the sky, a drawing-room at the bottom of a lake; monsters, mysteries; the poster for a vaudeville show raised horrors before me. Then I explained my magic sophisms with the hallucination of words.