Lyra is an orphan who lives in a parallel universe in which science, theology and magic are entwined. Lyra's search for a kidnapped friend uncovers a sinister plot involving stolen children, and turns into a quest to understand a mysterious phenomenon called Dust. She is later joined on her journey by Will, a boy who possesses a knife that can cut windows between worlds. As Lyra learns the truth about her parents and her prophesied destiny, the two young people are caught up in a war against celestial powers that ranges across many worlds.
Lyra and Will find themselves in a strange new place. The Magisterium take action as Mrs Coulter interrogates a suspected heretic witch, and Lee Scoresby embarks on a mission.
Lyra crosses into Will's world, and they set off to find answers about Dust. Will is shocked to discover he has grandparents, but quickly realises he can’t trust them.
Lyra ignores the alethiometer, with dangerous consequences for her and Will. Lee Scoresby’s search for Grumman brings an unlikely ally, and the witches seek answers.
In search of the knife, Will and Lyra try to gain entry into the Torre Degli Angeli. Lee finds Grumman - or Jopari, as he is now known - and they take to the sky in search of the knife bearer.
Will and Lyra plan to steal the alethiometer from Boreal but are set back by an unforeseen guest. MacPhail takes decisive action, and Mary takes a leap of faith.
Lyra and Will find allies who can help them in their search for Will’s father. The Magisterium learn something shocking, and Mrs Coulter meets a formidable foe.
As all paths converge on Cittàgazze, Lee is determined to fulfil his quest, whatever the cost. Mrs Coulter’s question is answered, and Will takes on his father’s mantle. Season finale.