It may only be spring, but I believe I have already found my book of the year.

Blackburn's 'biography' of the Norfolk fisherman-painter John Craske almost defies the category, eschewing a traditional linear structure and committing the cardinal sin of inserting the biographer herself into the life she is tracing. But it is so beautifully and hypnotically done that each page leaves you spellbound. Rarely can such an unusual telling so thoroughly, and so movingly, reflect the nature of the life being told.

John Craske was born in 1881. He followed his family's seafaring tradition, but soon after the beginning of the First World War, he became almost comatose with an unspecified illness. For the rest of his life, he would fall in and out of these stupors, as his long-struggling and loyal wife Laura held home and hearth together, often on a pittance. It is rare that working-class or impoverished writers and artists get the time to devote to their art, and rare for them to be remembered. That Craske managed to combat both debilitating illness and extreme poverty to achieve anything at all is remarkable.

What he did achieve was a vast number of paintings, on any paper or pieces of calico he could beg, borrow or steal, as well as embroidery, including a vast, unfinished tapestry of the Evacuation of Dunkirk. It was a friend of Blackburn's who suggested she might be interested in researching him, given that he came from the same local area as she did, and that she'd never heard of him. But in the late 1930s, he was 'discovered' by Valentine Ackland, who was the lover of the author Sylvia Townsend Warner. Ackland and Townsend Warner brought him to the attention of gallery owner Dorothy Warren who gave him his first exhibition and, for a time, a decent amount to live on from the sale of his paintings.

But Blackburn quickly found she was looking for "an absence". There was only a faint paper trail - mainly letters between an American enthusiast of Craske's work and Townsend Warner, and a somewhat haphazard journal kept by Craske's wife, Laura. And so Blackburn embarks on an old-fashioned search: one that involves walking about, talking to people who have relatives who might have known Craske or someone who knew him well, querying doctor's certificates and army dismissals. In all her books, she says, she has been attracted to people "who are in some way trapped by their own circumstances". In Craske, she uncovered a man "hemmed in on all sides by poverty and illness, combined with the curious wordlessness of his nature".

Given the untutored aspect of his painting, and the lack of a prominent mentor, Craske's work was rather patronisingly reviewed when it first appeared, and it wasn't long before he was forgotten entirely. But the tracing of his life story increasingly fascinates Blackburn, especially his turning to tapestry, which would have been hugely difficult to manage whilst he was lying prone in bed: "Sometimes I wonder if I have lost the thread, if there is a thread to be lost," she writes. But like many men traumatised after their experiences of war, he seems to have found the process of embroidery soothing as well as inspiring, and Blackburn seems to find the process of picking the threads of his life equally soothing and inspiring.

She needs this process to be so, because her husband, a sculptor, is suffering from a series of small strokes until one fatal day, he is felled completely. Just before he died, he told Blackburn that only work would get her through his loss once he is gone; the same is true of Craske, whose work gets him through the loss of physical action, the loss of his body in a way. Craske asks to be returned to the sea when he is at his most unwell, and it's at sea that he finds his inspiration, painting on his return boats and ships at sea, caught in the waves.

But this sorrowful ending to Blackburn's marriage is never hinted at in the beginning of her search. Her biography picks up various threads of Craske's life at different times and she follows that process meticulously, recording the minutiae of her dealings with local people, their conversations, their advice. She weaves in and out of her own story as she searches for his, constructing a meaningful and beautiful tapestry of her own that is as much a testament to a life lived as it is to the art that that life produced.