“I won’t hear a word said against Mr. Mifflin,” said Titania angrily.  “He’s one of my father’s oldest friends.  What would Mr. Mifflin say if he knew you had been breaking into his house and frightening me half to death?  I’m sorry you got that knock on the head, because it seems that’s your weak spot.  I’m quite able to take care of myself, thank you.  This isn’t a movie.”

“Well, how do you explain the actions of this man Weintraub?” said Aubrey.  “Do you like to have a man popping in and out of the shop at all hours of the night, stealing books?”

“I don’t have to explain it at all,” said Titania.  “I think it’s up to you to do the explaining.  Weintraub is a harmless old thing and he keeps delicious chocolates that cost only half as much as what you get on Fifth Avenue.  Mr. Mifflin told me that he’s a very good customer.  Perhaps his business won’t let him read in the daytime, and he comes in here late at night to borrow books.  He probably reads in bed.”

“I don’t think anybody who talks German round back alleys at night is a harmless old thing,” said Aubrey.  “I tell you, your Haunted Bookshop is haunted by something worse than the ghost of Thomas Carlyle.  Let me show you something.”  He pulled the book cover out of his pocket, and pointed to the annotations in it.

“That’s Mifflin’s handwriting,” said Titania, pointing to the upper row of figures.  “He puts notes like that in all his favourite books.  They refer to pages where he has found interesting things.”

“Yes, and that’s Weintraub’s,” said Aubrey, indicating the numbers in violet ink.  “If that isn’t a proof of their complicity, I’d like to know what is.  If that Cromwell book is here, I’d like to have a look at it.”

They went into the shop.  Titania preceded him down the musty aisle, and it made Aubrey angry to see the obstinate assurance of her small shoulders.  He was horribly tempted to seize her and shake her.  It annoyed him to see her bright, unconscious girlhood in that dingy vault of books.  “She’s as out of place here as—­as a Packard ad in the Liberator” he said to himself.

They stood in the History alcove.  “Here it is,” she said.  “No, it isn’t—­that’s the History of Frederick the Great.”

There was a two-inch gap in the shelf.  Cromwell was gone.

“Probably Mr. Mifflin has it somewhere around,” said Titania.  “It was there last night.”

“Probably nothing,” said Aubrey.  “I tell you, Weintraub came in and took it.  I saw him.  Look here, if you really want to know what I think, I’ll tell you.  The War’s not over by a long sight.  Weintraub’s a German.  Carlyle was pro-German—­I remember that much from college.  I believe your friend Mifflin is pro-German, too.  I’ve heard some of his talk!”

Titania faced him with cheeks aflame.

“That’ll do for you!” she cried.  “Next thing I suppose you’ll say Daddy’s pro-German, and me, too!  I’d like to see you say that to Mr. Mifflin himself.”