Throne of Ice and Ash - Paperback

The Stronghold of Telas:
Is a massive city made entirely of shining, silver metal-keeping Astriea and Seraphina imprisoned in the dungeons beneath it. With the group separated, Astriea and Sera do their best to understand the Telish royal family now holding them hostage. All while Thomas and Damian help the new King of Shadon ready for a war in her name.

To get them back.

But even as the sting of recent betrayal still haunts them, war with other countries would only aid their enemy. Astriea Blake sits in a cell and wonders how she can convince all three nations to turn their swords on this common foe, instead of each other.