Since nearly everything J.R.R. Tolkien wrote about Middle Earth has been published, the author’s estate has found new material by the famed author to publish. The Story of Kullervo, which was the first prose fiction he wrote, will hit bookstores this fall.

The book was announced on the Tolkien estate’s Facebook page on Aug. 7. It was never finished and is about a young man forced to work as a slave and seeks revenge for his father, who was killed by a magician.

According to the book’s official description, Tolkien called the book “the germ of my attempt to write legends of my own” and “a major matter in the legends of the First Age.” the publishers also note that Kellervo is an ancestor to The Silmarillion hero Turin Turambar.

The Daily Dot, that reference to the “First Age” also ties it into The Lord of the Rings mythology.

While the estate is billing this as a “previously unknown” story, the Daily Dot also points out that Kullervo was included in Verlyn Flieger’s collection Tolkien Stories. Fligler also edited the stand-alone version of Kullervo and added notes to the text for the new book.

The Story of Kullervo, which is based on a Finnish poem called Kaleva, will hit U.K. bookstores on Aug. 27. It won’t be out in the U.S. until October.