Sixteen-year-old Sarah Dullard lives in the New York of the roaring twenties, spending her summers at the luxurious Arlington Hotel, where her parents work.
But the summer of 1928 brings something different. First, the arrival of Peter Arlington, the owner's son. He's handsome, kind, and comes with a myriad of scandals behind him. And second, a mystery, just like the ones that Sarah reads in her pulp magazines. After a birthday party thrown by Peter, his friend, Will, disappears, starting a chain of dangerous events that reveal that something bad is happening inside the hotel.
While her parents try to calm the guests, Sarah and Peter try to find answers to what is happening. What those answers will reveal is a connection to a folk professor and the legend of a demon from the land of the rising sun.