Another book in J.R.R. Tolkien’s epic Middle-earth setting, The Fall of Gondolin, will be released this August, according to publisher Houghton Mifflin Harcourt.

Christopher Tolkien, who is 93, has edited and posthumously published more than two dozen collections of his father’s notes and unfinished work on the Middle-earth setting, as well as those on other subjects (like Beowulf and the work of translation). This announcement has surprised Tolkien scholars everywhere, because of how he had referred to 2017’s release of Beren and Lúthien as “(presumptively) my last book in the long series of editions of my father’s writings.” It seems, however, that “presumptively” was correct.

The elven city of Gondolin — and its sacking by the dark lord Morgoth — was “the first real story” of Middle-earth. J.R.R. Tolkien wrote the book while he was recovering in the hospital after serving in the Battle of the Somme, the largest battle in World War I and one of history’s bloodiest.

John Garth, author of Tolkien and the Great War, told the Guardian that The Fall of Gondolin is “a quest story with a reluctant hero who turns into a genuine hero — it’s a template for everything Tolkien wrote afterwards. It has a dark lord, our first encounter with orcs and balrogs — it’s really Tolkien limbering up for what he would be doing later.”

On a more canonical timeline, Gondolin significantly predates the events covered in the Lord of the Rings movies and books, although there are references to it even in The Hobbit. Orcrist, Glamdring and Sting, the three swords that Gandalf, Bilbo and company retrieve from the trolls’ hoard are all ancient weapons made in Gondolin — hence their particular use for killing orcs.

Houghton Mifflin Harcourt

Gondolin was founded by the elven king Turgon in the First Age of Middle-earth (the events of the Lord of the Rings take place many thousands of years later, marking the end of the Third Age and the beginning of the Fourth). It was a secret city hidden inside a ring of mountains, accessible only by a secret pass that was revealed to Turgon by Ulmo, the elven deity of water. It stood for 400 years, before its location was revealed to the dark lord Morgoth — of whom Sauron was merely a servant — by Turgon’s nephew Maeglin. Morgoth’s army of orcs, dragons, balrogs and other horrors overthrew the city, and only a handful of its citizens escaped via secret passage.

But outside of battle and conflict, the Fall of Gondolin also contains a classic Tolkien story of love, jealousy and betrayal: Maeglin coveted Turgon’s daughter (his cousin) Idril, but Idril had fallen in love with and married Tuor, a human man. It was Morgoth’s promise that he would rule Gondolin with Idril at his side that motivated Maeglin to betray his people, and it was Idril who had the foresight to prepare a secret way of escape.

And that’s a good thing, because Idril and Tuor wound up being Elrond’s grandparents — which means they’re also really, really, really, really removed grandparents of Aragorn, too.

All of this was covered from a macro-perspective in The Silmarillion, published in 1977, but this new book promises to delve into the story more deeply and in a novelistic style. All of this is good news for the folks behind Amazon’s upcoming Lord of the Rings adaptation — at least, depending on exactly which parts of the history of Middle-earth will be depicted in the show.