Isabel Allende has taken the Premio Planeta, the Spanish literary prize worth €1m (£843,000), with La hora antes del alba - a manuscript the 84-year-old entered under the name Luz Ventura.

A secret entry, a €1m prize

The award, celebrating its 75th edition, was announced on Thursday at a ceremony in Barcelona attended by King Felipe VI and Queen Letizia. The prize accepts unpublished manuscripts and permits pseudonymous submissions, and Allende made use of both: her entry carried the invented author name Luz Ventura and the fictional title Los que faltan.

A sequel to The House of the Spirits

The winning book is a sequel to Allende's 1982 debut, The House of the Spirits. According to Reuters, it follows Alba - granddaughter of Esteban Trueba and Clara del Valle - as she tries to recover from imprisonment and torture during Pinochet's dictatorship. Allende was prompted to write it by decades of readers asking what happened to Alba, and said the book would bring the universe of The House of the Spirits to a close.

The author's own words

Accepting the award, Allende described the moment as "like winning the Nobel". She also admitted the pseudonym route answered an old hesitation about competitions: "I had never entered a competition because I wanted to avoid the embarrassment of coming last," she said, adding that at her age there was little to lose.

The prize and the pseudonym game

The prize has a history of hidden identities, and this year's conditions come from the publisher behind it.

• •The prize is run by Planeta, one of the largest Spanish-language publishing groups, on condition that the winning book be published by them.
• •In 2021 the award went to La bestia, published under the pseudonym Carmen Mola, who was revealed at the ceremony to be three male writers - Jorge Díaz, Agustín Martínez and Antonio Mercero.
• •The runner-up this year was the Spanish writer and screenwriter Sergio Hernández, whose historical novel La añoranza won €200,000.
• •Past winners have included prominent Spanish-language authors such as Juan Marsé and Manuel Vázquez Montalbán.

Academics were sceptical that the secrecy ran deep. Prof Duncan Wheeler of Leeds University said: "I'd be very surprised if the judges did not know that it was Isabel Allende", noting that while the prize is generous, it is not the most prestigious in the Spanish-speaking world.

Allende, whose books have sold more than 80m copies worldwide and been translated into more than 40 languages, has been published since her debut by Plaza & Janés, an imprint of Penguin Random House, and her win is a coup for Planeta. The winning book will be published by Planeta, as the prize's terms require.