The BBC and HBO unveiled a new trailer for their upcoming TV series, His Dark Materials, showing off a fantastical world where a war is brewing between an authoritarian Church and those who resist it.

Based off the book series by Philip Pullman, the series is set in an alternate world where every person has their own shapeshifting, animal-shaped companion, a manifestation of their soul. These companions are called Daemons. The story follows a young girl named Lyra Belacqua (played by Logan’s Dafne Keen) who grows up as an orphan in Oxford. When children begin vanishing, including her best friend Roger, she sets off into the Arctic to find him, and discovers a conspiracy involving her world’s domineering Church.

This latest trailer shows off the stakes of the war that’s brewing between the Church and its opponents. Lyra is caught in the middle: her uncle, Lord Asriel (played by James McAvoy), is one of those who resist the Church. Church agent Mrs. Coulter (played by Ruth Wilson) takes Lyra under her wing for nefarious purposes, and it soon becomes clear that she’s up to some fairly twisted experiments involving children. Along the way, Lyra picks up an oracular device called an aletheometer, meets aeronaut Lee Scoresby (played by Lin-Manuel Miranda) and armored polar bear Iorek Byrinson, and recruits them to help her free her friends and disrupt the Church’s plans.

His Dark Materials is a dark, anti-authoritarian trilogy (plus a recently released prequel, The Book of Dust) that explores the nature of ethics and consciousness. The first attempt at a film adaptation, 2007’s The Golden Compass, failed to live up to box-office or fan expectations, and the filmmakers never went on to adapt the other two books in the series. From this latest trailer, it looks as though HBO is positioning the series as a potential successor to Game of Thrones, which just aired its last season back in May. The book series certainly has the components to be the next big fantasy adaptation — it has a fantastic cast of characters, a plot loaded with relevant political allegory, and plenty of action and world-ending stakes.

HBO hasn’t revealed a release date for the show’s launch, teasing only that it’ll be released this fall.