In 1849, Herman Melville sailed for Britain, leaving his young family behind in New York. His ostensible purpose was to gather material for a fiction based on the story of Israel Potter, a revolutionary soldier who became a "legend in his own time".

But, as Jay Parini tells it in this fictional account of Melville's life, Potter proves too elusive, leaving Melville wondering whether he should simply make up his story – perhaps drawing on his subject's autobiography for inspiration. Eventually the idea of writing about Israel Potter recedes as Melville, disillusioned, begins to assemble material for a very different kind of book: a tale of obsession, provisionally entitled Mocha Dick.

There are several moments like this in Jay Parini's novel, where sketches of Melville at work lead into explorations of Parini's own creative practice. Parini is a biographer and critic as well as a novelist, and he has made the biographical novel his own, through depictions of Leo Tolstoy and Walter Benjamin. The Passages of Herman Melville sets out to demonstrate that "only novels tell the unadorned truth", and, in so doing, to make a claim for the value of its genre. "Everyone knows that the truth can't be told, not in historical writing," a friendly observer tells Melville at one stage. "You have to make it up, else nobody will believe you."

Parini does not have to make up the events of Melville's life, but he does have to fill considerable gaps in his subject's biography. Melville left few letters and, despite his fame, is in many ways as elusive a figure as Israel Potter. In attempting to dramatise his consciousness Parini therefore sets himself a monumental challenge. He meets this challenge by interweaving two narratives: a third-person retelling of Melville's passages across land and sea, and a first-person depiction of Melville at home, told through the eyes of his wife, Lizzie.

We know little about Lizzie Melville, and in developing her voice Parini lets his imagination roam freely. Perhaps for this reason, it is here that Melville comes most vividly to life. For much of the novel Lizzie is alienated from her husband, dismissive of his work and resentful of the damage he does to her family. Yet, through her, Parini conjures into being a difficult, contradictory character animated by his emotional fragility. Some of the novel's most touching scenes come at its close as Lizzie overlooks Melville's many failings to sympathise with his sorrows and – briefly – to admire his prose.

The problems with the book occur when Lizzie is absent from its pages. The Melville of the novel's third-person "Passages" narrative is a distant figure, particularly when he meditates on his writing. This is despite the fact that in these sections Parini incorporates Melville's own words into his prose. Biographical events transmute into art so straightforwardly as to render the account of Melville's creativity strangely literal, even reductive. Aboard the Acushnet, Melville realises with a "shudder of quiet pleasure" that his experience "might find itself one day in a work of fiction by his own hand", the narrative continuing to signal the links between work and life: "He knew it would, and vowed to listen keenly, to watch and record in his journal whatever transpired."

Here, and elsewhere, The Passages of Herman Melville feels overemphasised. But there is much to admire. The novel powerfully conveys the allure of the sea, and of the ships that do battle with its creatures. And Parini's evocation of Melville's relationships is moving. Melville may be a bad husband and a needy friend, but there is something admirable about the passion with which he responds to those around him. In his dealings with his wife, his friend Nathaniel Hawthorne, and the young men who people his story, he becomes a tragic figure, finally rendered heroic by his capacity to feel.