J.K. Rowling has written three collections of short stories that take readers deeper into the “dark side” of the Harry Potter wizarding world, publishers confirmed Wednesday.

Rowling reveals surprises and intricate details about several characters’ lives in the three new ebooks, which are available next month, Pottermore CEO Susan Jurevics said in a statement to TIME. The collections are presented by Pottermore, the interactive website Rowling created for Harry Potter fanatics, and cost about $3 each and will be released Sept. 6.

“Pottermore Presents is intended to supplement the Harry Potter book series with short-form content that is entertaining and thematically curated by the Pottermore editorial team,” Jurevics said.

Each book is about 10,000 words long and is being sold on Pottermore and other online book retailers.

Power, Politics And Pesky Poltergeists gives readers a glimpse into the “ruthless roots” of Professor Dolores Umbridge and the relationship between Professor Horace Slughorn and Voldemort when the Dark Lord was a young student at Hogwarts. The book also provides the history behind the Azkaban prison.

Heroism, Hardship and Dangerous Hobbies profiles Minerva McGonagall and Remus Lupin, while Hogwarts: An Incomplete and Unreliable Guide focuses on secrets behind the walls of the wizarding school.

The stories, which are available Wednesday for preorder, come after Rowling said the eighth installment in the beloved book series, Harry Potter and the Cursed Child, will be the last story about Potter in the saga.

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