The older he gets, the more difficult Mario Vargas Llosa becomes. It's not that his work is more obscure or challenging, but he makes things increasingly hard on himself. He writes about historical figures but seems unsure of his ability to fictionalise them. At every step of The Way to Paradise, he reaches out anxiously towards his characters, Paul Gauguin and Gauguin's grandmother, the social reformer Flora Tristan, and addresses them directly. He veers erratically between the third and the second person: “He laughed, then grew distressed. Why were you remembering your mother now? He hadn't thought of her since 1888, when he painted her portrait.”

All that seems certain is that he and his grandmother spent their lives seeking the way to paradise. Flora believed that she could build utopia on earth. Her vision of a Workers' Union, in which they would own all the means of production and share profits equitably, led her on an endless tour of French factories, preaching to workers who were mostly too exhausted to be converted. Fifty years later, her grandson nurtured dreams of a more private paradise, “where art wouldn't be just another business venture but a sacred, vital and sporting task, and where to eat, an artist would only need to raise his arm and pluck fruit from heavily laden trees, like Adam and Eve in the Garden of Eden”.

Both dreamers' idealism closely relates to narcissism. Flora has rejected the Catholic Church, but her work is infused with a Christian sense of purpose. Gauguin's egomania is more overt, raised to the level of a pseudo-religion. His island paradise is a shrine to his own desires, sexual, alcoholic and artistic. Certainly, his behaviour brings him into conflict with the Church, as did his grandmother's plain speaking, but there is nothing revolutionary about it. He blights his idyll with syphilis, and the negligence with which he treats his pubescent wives.

In real life, neither Paul nor Flora found Eden, but their failed attempts inspired many others to follow their example. Flora's socialism and Paul's sensualism opened the door not to paradise, but to the 20th century; the genetic connection between the two characters inspires Vargas Llosa to find a link between these two facets of modernity. Did Flora's social radicalism lead inexorably to Paul's libertinism? Is there a narcissistic element within even the most selfless of crusades?

Vargas Llosa does not answer these questions, but his sympathy for Gauguin conflates the two very different quests for paradise. When a friend sends Gauguin a new model, it is not long before she is on her back: “That same night, Paul made her his lover.” Gauguin is judged on his own terms as a revolutionary dreamer, not a sexual predator. Flora, meanwhile, is granted the benefit of hindsight whenever her recorded thoughts are not in line with Vargas Llosa's high opinion of her. In her autobiography, Peregrinations of a Pariah, she included phrases such as “the smell of the negro, which defies comparison, making one ill and lingering everywhere”. Vargas Llosa cajoles her for it: “The smell of the negro! How you later lamented that silly, stupid remark, the repetition of a commonplace among Parisian snobs.” Yet the remark is there, in print, while the lamentations are all imaginary.

It is this inability to leave his characters alone that lets the book down. Vargas Llosa combines the most Whiggish kind of history with a novelist's disregard for the truth. This leaves him in a lonely place, somewhere between fact and fiction, where the novel reads like the shadow of a historical account that has been lost.