In 2010, the bestselling American novelist Jodi Picoult complained that her work was suffering from sexism. Her 30 novels address weighty subjects from gay rights to gun control, and if they were written by an author such as Jonathan Franzen or Jeffrey Eugenides, she believed they would not be perceived as beach reads.

Picoult’s gripe has culminated in By Any Other Name, a novel in which Emilia Bassano, first proposed by the historian AL Rowse as the mysterious Dark Lady, is not Shakespeare’s mistress but the author of Shakespeare’s work. Virginia Woolf wrote an essay imagining the dismal fate of Shakespeare’s sister, whose “genius was for fiction and [who] lusted to feed abundantly upon the lives of men and women and the study of their ways”, but imagining that the Bard might have been a woman, as opposed to a bisexual man, would challenge any author.

In modern Manhattan, Melina is a young playwright whose confidence has been crushed for a decade by an unkind review of her debut. A descendent of Bassano, she dramatises her conviction that Emilia must have written Shakespeare in a new play. How, she argues, could a glover’s son from Stratford without an Oxbridge education know about court manners or the Danish castle in Hamlet, or a particular Italian fresco mentioned in Othello? Bassano, a ward of aristocrats, was someone whose family of converted Italian Jews were musicians at Elizabeth’s court. How, too, could Shakespeare have created such proto-feminist heroines as Portia, Beatrice, Rosalind, Viola, Cleopatra and Lady Macbeth when he didn’t even teach his daughters to sign their own names? “Every gap in Shakespeare’s life or knowledge that has to be explained away by scholars, she somehow fills,” Melina claims.

The conviction that Shakespeare wasn’t posh or pretty enough to have written Shakespeare is a favourite joke to those who satirise conspiracy theorists. The facts of Shakespeare’s life could be written on a postcard. He used others’ plots, but how did his matchless sensibility and style evolve?

Ben Elton’s comic series Upstart Crow presented the Bard as a hack stumbling into great lines when prompted by domestic irritations. In the Tudor chapters, Emilia, too, utters lines that become famous in Hamlet and elsewhere via her apprehension of the injustice of women’s lives. As concubine to the Lord Chamberlain, who must read every new play submitted for a licence, Emilia can hone her craft, but only her friend Kit Marlowe can know of her gifts. Desperate for money, she chooses a talentless player to be her beard, one Will Shakespeare: “kind of a jerk”, as Picoult observes in her afterword. (Clearly, she has not encountered any real-life male writers if she believes this disqualifies him as an author.) He reaps the fame, and she gets her work out to the public for a pittance.

One problem is that Picoult’s Tudor heroine is basically a 21st-century American feminist who notices “pops of colour”, but nothing about the human condition. One never feels the roil of a gifted writer’s language, observation and ideas. The best approach him obliquely: Maggie O’Farrell’s Hamnet had the wisdom to portray Shakespeare through his wife Agnes’s eyes, and Tom Stoppard’s Shakespeare in Love is transformed by youthful, life-changing passion. Nothing explains how or why Shakespeare’s work became a mirror in which we each see our own selves. We cannot pluck out the heart of his mystery.

Had this novel’s 500-plus pages been ruthlessly edited, it might have been a diverting romp. As it is, the modern-day parts of By Any Other Name add nothing but polemic. Like Emilia, modern Melina hides her work, in her case behind the identity of her gay Black best friend, leading to predictable professional and romantic complications. In Tudor England, Emilia’s life has a more compelling arc. Sold as a concubine at 13, conducting a passionate affair with Lord Southampton, forcibly married to the abusive Alphonso Lanier, she has a son, fights off the plague, and writes sublime plays and sonnets before dying in obscurity.

The theory that Shakespeare was a woman was, as Picoult acknowledges, first put forward by the academic Elizabeth Winkler in a 2019 essay in the Atlantic, and then in a book published last year. If it helps to combat the sexism that has serious female authors fighting not to have headless torsos in pink on our jackets, it is welcome. However, anyone who writes such sentences as “she drank from him as if he were an elixir” has not, perhaps, read even their own work attentively.

Picoult’s descriptions of Emilia’s silver eyes, clothes and orgasms plus her campaigning sense of social justice and propulsive storytelling are why she sells 40m copies worldwide. She is not, however, writing the same kind of fiction as Eugenides or Franzen. Commercial or literary? Only a genius gets to be both.