Shadowrise by Tad Williams
The Eddon family is divided and scattered. King Olin is a prisoner of the mad autarch of Xis, whilst Prince Barrick is lost beyond the Shadowline, searching for the fabled Qar capital. Far to the south, Princess Briony is a reluctant guest of the Syannese court. The Qar continue their siege of Shadowmarch, but Hendon Tolly is more interested in unearthing the ancient secrets of the castle than in resisting the invaders. That job falls to the Funderlings, who must mount a stalwart defence of the tunnels and passages below the castle. Shadowrise is the third novel in the Shadowmarch series. Originally planned as a trilogy, the final book in the series grew too large to publish in one volume, so was split in half (though each half is almost as long as the first two books in the series by themselves). Williams has form on this, as this also happened with the paperback edition of the final volume of the Memory, Sorrow and Thorn series. As with the first two books in the sequence, Shadow...