A sleuthing English professor looks into the sordid secret life of a student who's gone missing . . .

When a young woman comes to Professor Pennyfeather and confides that her cousin Ernestine—one of his English students—is missing, he's surprised to hear that the bookish girl in his class is a very different person outside of school. Apparently, in the evenings, she transforms herself into a femme fatale and looks for naïve young sailors at the waterfront dancehalls, enjoying fancy nights out at their expense before verbally abusing and abandoning them. Now she hasn't been seen in two days, and her cousin fears she's taken one too many risks. The professor decides it's time to do some research. He wants to know what happened to Ernestine, and what caused the orphaned heiress to pursue this secret life—one that just may have led to her death . . .