EXCLUSIVE: The BBC has doubled the order of its adaptation of Philip Pullman’s His Dark Materials ahead of its debut.

Deadline understands that the Bad Wolf and New Line production has already been handed a second, eight-part season. Filming kicked off earlier this month in Cardiff at Wolf Studios Wales for season one of the drama, which is thought to be one of the most expensive British scripted series to date.

The series stars James McAvoy, Dafne Keen, Ruth Wilson and Lin-Manuel Miranda, is written by Jack Thorne and directed by Tom Hooper.

In March, Deadline revealed that Logan star signed up to play main character Lyra, an orphan, who lives in a parallel universe, alongside Hamilton creator Lin-Manuel Miranda, who plays adventurer Lee Scoresby. McAvoy plays Lord Asriel, father of Lyra, while The Wire’s Clarke Peters, who recently starred in Three Billboards Outside Ebbing, Missouri, plays the master who raises Lyra. The Affair’s Ruth Wilson plays Marisa Coulter, one of the main protagonists and the former lover of Lord Asriel. Rogue One’s Ariyon Bakare plays Lord Boreal, an antagonist in the books, who charms Lyra and houses her from the police before stealing her alethiometer.

The cast also includes Black Mirror’s Georgina Campbell, Shameless’ Anne-Marie Duff and Games of Thrones’ Ian Gelder, while Wolf Hall star Will Keen, father of leading actress Dafne Keen, plays Father MacPhail.

Hooper will be lead director of the big-budget adaptation of Philip Pullman’s fantasy epic and helm the first two episodes with Dawn Shadforth (Trust) directing an episode and Peaky Blinders’ Otto Bathurst directing two.

His Dark Materials is produced by Bad Wolf and New Line Cinema for BBC One in association with BBC Studios Distribution and Anton Capital Entertainment. Endeavor Content co-reps North American rights with BBC Studios Distribution.

It is exec produced by Pullman, Thorne, Tranter, Gardner, Dan McCulloch, Toby Emmerich and Carolyn Blackwood for New Line; Piers Wenger and Ben Irving for BBC One and Deborah Forte for Scholastic.

It is based on Pullman’s trilogy of books: Northern Lights, The Subtle Knife and The Amber Spyglass, a complex tale of physics, philosophy and theology featuring witches and armored polar bears. It tells the story of two children, Lyra and Will, who wander through a series of parallel universes.