JANET MALCOLM'S biography of Gertrude Stein and Alice B. Toklas is entitled Two Lives. But the life to which she devotes most attention belongs to neither subject.

This book is an account of its own genesis — Malcolm's lifelong fascination with Stein and Toklas, her progress through Stein criticism, her encounters with Stein scholars and the whole investigative process. Implicitly, she presupposes that the reader engages with the mechanics of her writing. “Jennifer's Diary”-like, she lovingly describes her sources. We read that one “is an attractive and vigorous woman of 80, with an excellent memory” — although the average reader's interest extends only to the information this sparky octogenarian has.

Such an approach is surprising. Malcolm repeatedly theorises about biography, condemning its “flaccid narrativity” and the biographer's “arrogant desire to impose a narrative on the stray bits and pieces of a life”, an argument at odds with her omnipresence throughout Two Lives and the alternative narrative that she describes. Readers familiar with the modernist assumption that a text exists whole within itself, distinct from an author's life, will be surprised that in her quest to capture Stein, the pre-eminent literary modernist, Malcolm consistently asserts herself.

None of which is to say that Two Lives is unsuccessful or unenjoyable. Malcolm's account of US Stein-criticism is fascinating. By framing her version of Stein's life within the story of how she reached it, she humanises her subject and, in conveying the origin of her own fascination, she increases ours. What she never does is simply give in and write anything approaching straightforward biography.

Two Lives asks three questions: “How did this pair of elderly Jewish lesbians escape the Nazis? Why did they stay in France instead of returning to the safety of the US? Why did Toklas omit any mention of her and Stein's Jewishness (never mind lesbianism)?” The answers contribute the majority of the biographical element: Malcolm confines herself to a snapshot of those two lives at a specific moment — the second half of the Second World War. Over and over, she returns to the issue of their Jewishness. Her discussion of Stein's writing is elegant and illuminating. Her engagement with her — or Toklas's — life lacks the same excitement.

Two Lives: Gertrude and Alice by Janet Malcolm
Yale, £16.99

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