Once a city of enormous wealth and culture, Prague was home to emperors, alchemists, astronomers, and, as it’s whispered, hell portals. When music student Sarah Weston lands a summer job at Prague Castle cataloging Beethoven’s manuscripts, she has no idea how dangerous her life is about to become. Prague is a threshold, Sarah is warned, and it is steeped in blood. Soon after Sarah arrives, strange things begin to happen. She learns that her mentor,...