The BBC has released a new video of our hardwork in the Brecon Beacons. It took six weeks to construct the village in its entirety.
Be careful: spoilers ahead!
In the clip, you'll see the whole development, where Lyra meets the polar bear and confident aeronaut, Lee Scoresby, for the first time.
Watch the last episode on BBC iPlayer. The fifth episode will be broadcast this Sunday at 8:00pm on BBC1.