A good novella is an ideal companion for a three- or four-hour trip. It's slim enough to tuck in your hand luggage, brief enough not to add to your travel tiredness, yet provocative enough to reward you with a satisfying read. Think of Scott Fitzgerald's The Great Gatsby or John Steinbeck's Of Mice and Men, both of which deliver much more than their brevity would suggest. It's also a form well suited to tense and eccentric narratives, because the limited space concentrates the prose and intensifies the atmosphere. Yet it was another well-known novella, Albert Camus' The Outsider, that kept coming to mind as I read The Lone Woman by the celebrated Basque writer, Bernardo Atxaga.

Whereas Camus' existentialist classic follows his hero, Meursault, from freedom to incarceration and imminent death, Atxaga's novella reverses the plot while retaining the vision of an individual fervently committed to the truth, however circumspect. Atxaga's defiant heroine, Irene, has just left prison having served a sentence for terrorist activity as part of a "radical political organisation". After spending a torrid night in Barcelona, she embarks on a long bus journey home to Bilbao, during which she is haunted by memories and dreams and by fragments of books that she'd read during her time inside. Not to mention the two policemen who are on board. Having divorced her husband, lost her lover and been scorned by both her family and her political group, Irene confesses that "I'm a traitor now", and declares herself "ready to accept the smallest sign of love".

In taut, elegant sentences which generate a sense of restlessness and foreboding, Atxaga reveals the uncertain mind of a fugitive fleeing the past and, by identifying only the salient details in each scene, he creates a disturbing, transitory world in which all proportion and compassion have been lost. The characters outside the prison walls, for example, are not given names. Instead, they are referred to as "the man with the red tie", "the nun with the green eyes", "the passenger who looked like a boxer".

Such a strategy delicately reinforces Irene's isolation; she has, after all, just been released from the gloomy uniformity of prison into a world of difference and light. The sky, symbolising freedom and a focal point for her yearning, is similarly important.

In the final paragraph of The Outsider, Meursault famously looks up at the night sky from his cell and accepts "the benign indifference of the universe". Although Irene has similar thoughts, her frequent star-gazing is more hopeful. With this and other light touches, Atxaga convinces us that this woman has done her time.

The furtive prose stalks the reader with the promise of disclosure, but in novellas it's what is left unsaid that resonates. "Was it possible to live without love?" wonders Irene. This is the tantalising nature of Atxaga's fine novella: its precision and concealed wisdom leave us wanting to hear more from his exceptional heroine. But then, you can always read it again on the way back, can't you?