When Lyra's friend Roger disappears, she and her daemon, Pantalaimon, set out to find him.

They travel to the ice kingdoms of the North, where armoured bears rule and witch-queens fly through frozen skies.

Lyra possesses a device that will aid their quest - if she can decipher its mysterious messages.

But it knows terrifyig secrets about their journey, and the dangers that await them in worlds far beyond their own