Margaret Atwood has announced a sequel to her bestselling feminist dystopian novel The Handmaid’s Tale, titled The Testaments. It will be published in September 2019.

“Dear Readers,” wrote Atwood in a press release announcing the book on Wednesday. “Everything you’ve ever asked me about Gilead and its inner workings is the inspiration for this book. Well, almost everything! The other inspiration is the world we’ve been living in.”

The Handmaid’s Tale follows one woman’s struggle to survive in a dystopian future America, renamed Gilead, where women possess few rights, are used as breeding vessels and are not allowed to read or write. The novel was first published in 1985, and quickly recognised as a modern classic.

It has sold more than eight million copies in English and has gained a new readership in recent years, because of its perceived relevance amid global discussions of sexual harassment, abortion rights and the rise of populist politicians such as Donald Trump. The critical success of the 2017 television adaptation, starring Elisabeth Moss in the lead role of Offred has also helped extend the book’s audience.

The Testaments will be set 15 years after Offred’s final scene in The Handmaid’s Tale and narrated by three female characters. It will not be connected to the television version, which has extended beyond Atwood’s 1985 novel to continue Offred’s story.

The novel ends enigmatically, with Offred being placed in a van that will possibly deliver her to freedom outside Gilead. An epilogue is narrated by an professor delivering a lecture about the authenticity of Offred’s story in the year 2195, based on cassette tapes he discovered in Maine.

“As a society, we’ve never needed Margaret Atwood more,” said Becky Hardie, deputy publishing director at Chatto & Windus. “The moment the van door slams on Offred’s future at the end of The Handmaid’s Tale is one of the most brilliantly ambiguous endings in literature. I cannot wait to find out what’s been going on in Atwood’s Gilead ­– and what that might tell us about our own times.”

Demonstrators dressed as handmaidens awaiting the arrival of Brett Kavanaugh prior to his confirmation hearing for the US supreme court in September. Photograph: Joshua Roberts/Reuters

After the success of the television adaptation, the distinctive red robe and white bonnet of the handmaidens began to be adopted as a symbol of female oppression. with silent protesters donning the costume at pro-choice rallies in Argentina and Ireland, and at the September hearings for US supreme court judge Brett Kavanaugh, after he was accused of sexual assault. In 2017, Atwood’s novel spent 16 weeks on the Sunday Times bestseller list, while UK publisher Vintage reported a 670% year-on-year increase in sales.

Atwood has previously teased a sequel, most recently in an audiobook adaptation for Audible. At the end of the epilogue, she added a Q&A session that ended with the lecturer saying: “I hope to be able to present the results of our further Gileadian investigations to you at some future date.”

“I am in consultation with the professor, but he is being very cagey about this,” Atwood told Canadian website the Loop at the time. “He evidently doesn’t want to make any promises before he has finished authenticating his new discoveries.”