It also details an adventure of Miss Titania Chapman and a young advertising man named Aubrey Gilbert.

Throughout the novel Morley, through the character of Roger Mifflin, makes reference to the knowledge and wisdom that one can gain from literature.

The narrative begins with a young advertising man, Aubrey Gilbert, stopping by a bookstore named "The Haunted Bookshop" in the hopes of finding a new client.

Gilbert does not succeed in selling advertising copy, but is intrigued by Mifflin and his conviction concerning the value books and booksellers have to the world.

Meanwhile, mysterious things start to happen: a copy of Thomas Carlyle's Letters and Speeches of Oliver Cromwell disappears and reappears, Gilbert is attacked as he travels home, a pharmacist neighbor of Mifflin is observed skulking in the alley behind the bookstore at night speaking to someone in German, and an assistant chef at the Octagon Hotel has posted an ad in The New York Times promising a reward for a lost copy of Letters and Speeches of Oliver Cromwell.

He suspects that the gregarious Mifflin is involved in a plot to kidnap Titania, and he assigns himself the job of protecting her.

Gilbert takes a room across from the bookstore in order to keep eye on things, and believes his suspicions confirmed when he sees the pharmacist let himself into the bookshop with his own key late at night.

Gilbert breaks into the bookshop in an effort to find evidence to prove his suspicions, but only manages to frighten and anger Titania.

In the final chapter of the book Gilbert and Mifflin learn what the true plot was: The pharmacist was a German spy who had been using the bookshop as a drop-off point.