In Evernight Harbor, where the sun never shines, a mysterious whisper is spreading through the streets and alleys. Anyone who hears it dies under strange circumstances within three days. Erin, a former linguist, is drawn into this eerie mystery while searching for her missing younger brother. She discovers that the whisper is no random curse, but the way some conscious being is revealing itself through human language. As her investigation deepens, Erin realizes that the entire city is little more than a giant incubator, and she may be the only person capable of understanding the truth.