Beneath the Rumbling Earth by Anna Tan

In the Deep where none dare go Beneath the rumbling earth Before the Flame is doused You must rekindle birth The curse should have been broken now that the King of Winter's spirit has been released from the castle. But the Dragon has yet another prophecy, and the creatures in Painted Hall have finally found their voices. Beneath the Rumbling Earth (North #3) brings you back to the City of Winter and into its hidden fiery depths.