Millennia ago, a magical race called the Aesir found a new home on a distant world. Attracted to the cold during an ice age, they hibernated for hundreds of years at a time. With each awakening, however, they saw their world changed by ever-evolving mortals encroaching on their territory and way of life. Two civilizations with opposing magic, poised to clash over and over. Now, the Aesir are awakening to wage a new war--this time to exterminate their enemy once and for all.

Robinson Hawksley is an elocutionist at the Invisible College who has perfected a way of teaching speech to train sorcerers by using the intelligences that create magic. The world needs more sorcerers to protect against the looming Aesir threat, and Robinson's newest charge is McKenna Foster, a barrister's daughter rendered deaf after a bout with a plague unleashed by the Aesir. As their lessons progress and they grow ever closer, there also comes a strange connection to the Aesir--one that crosses the boundaries of time itself and the unfathomable mysteries of the Unseen Powers.

Emerging from their icy fortresses, the Aesir begin their bombardment. Can Robinson and McKenna, brought together by magic, stop an endless war with powers even they have yet to fully understand?