His Dark Materials, the BBC-HBO adaptation of Philip Pullman’s best-selling fantasy trilogy, has returned to our screens. Here the cast and crew of series 3, including Ruth Wilson (Mrs Coulter) and Amir Wilson (Will Parry), visit the BFI IMAX to introduce the final series of the show and explain what’s happened to Lyra Belacqua and how her father’s battle against the Authority is about to come to a head.