It is a sequel to The Handmaid’s Tale (1985).
The novel is set 15 years after the events of The Handmaid’s Tale.
It is narrated by Aunt Lydia, a character from the previous novel; Agnes, a young woman living in Gilead; and Daisy, a young woman living in Canada.
Spoiler – Agnes and Daisy are the daughters of June Osborne / Offred / Ofjoseph (Elisabeth Moss in the TV series).
The highlight of the sequel is Aunt Lydia, for sure. Her backstory. Her rise to power as an Aunt overseeing the women of Gilead. Atwood said that Dowd’s performance as Aunt Lydia on the series helped inspire the new novel
Ann Dowd plays the Aunt Lydia role in the TV series. And she reads the part in the audio book.
My only quibble with the otherwise very good book is the plot. It’s absurd to think this was the only way to get Aunt Lydia’s Testaments to Canada. Absurd.