Darkness has fallen on Aveline since Kaethe barred the gates to the underworld. The dead roam unchecked, immune to iron and other weapons. A ruthless child queen has risen in the west, and her armies of the night are marching. It's not a fight Cas or Lo wanted, but they're swept into the thick of it regardless. Having fled one besieged city, Cas must see his family safely to the Boundary, a pilgrimage through lands shattered by war and haunted by ghosts. He meets an old friend along the way - but surviving will mean facing deeper truths about his own path. Half a continent away, Lo is chasing a fugitive god and the ancient necromancer who holds him in thrall. The hunt leads to the frozen reaches of the Icemarch - and a reckoning with hidden puppet-masters who've been tugging her strings. Meanwhile, a crucial battle looms at the mountain pass called Hellgate. Lucius must face the Redvaynes again - but this time as a free man instead of a slave. Get the thrilling conclusion to the Fourth Empire series today!