Death at the fair

Emily Cabot, one of the first female graduate students at the University of Chicago, invites her mother and brother to join her in the city to attend the 1893 World's Fair, along with her teacher Dr. Stephen Chapman. At the fair, Chapman turns pale as a ghost when he runs into a woman who turns out to be an old flame. When her husband is killed and Chapman is found by the body, it is up to Emily and a rotating cast of advisers - some recognizable from history, some not - to free him.