The Mad Hatter Mystery by John Dickson Carr

Lord Bitton had appealed to Chief Inspector Hadley to investigate a theft which had taken place at his home. Lord Bitton was a collector of books and manuscripts so Hadley had invited Gideon Fell, an expert in this subject, to attend this meeting. It seems that Bitton had visited the Edgar Allen Poe house in Philadelphia and observed that a manuscript had been uncovered in a wall by some workmen. Bitton stole the manuscript, returned with it back to England, and would not tell anyone, even his family, what story it was . Now the manuscript had been stolen from its hiding place in his home.

Meanwhile, someone was stealing the hats of Londoners and putting them in unlikely places. The London newspapers were calling the thief The Mad Hatter, a name which had been started by a cub reporter by the name of Philip Driscoll who was the nephew of Lord Bitton. A cabby's horse was seen wearing a barrister's wig. The hat of a member of the stock exchange was found on one of the lions at Nelson's monument in Trafalgar Square.

Lord Bitton's hat had been stolen just an hour and a half before he arrived at the meeting with Hadley and Fell to discuss the matter of the theft of a Poe manuscript. Then they received the news that the body of young Driscoll had been found on the steps of the Traitor's Gate at the Tower of London, and that the body was wearing Lord Bitton's hat. The meeting was immediately moved to the Tower of London. Suspects were interviewed, but very little was learned, and no one had witnessed the murder which had been done with a souvenir blade from France. Curiously, several people who could be involved with the manuscript theft were also sight seeing at the tower that day.

Further investigations would show the involvement of Lord Bitton's brother, Lester and his wife Mary.  They had a daughter, Sheila, who was a rather flighty young lady who planned to marry Mr. Dalrye who had been a very good friend of Driscoll. There was also the American manuscript collector, Mr. Acton, who said little but who knew more about the Poe manuscript that he was letting on. Of course, Gideon Fell solved the whole puzzle, but he seemed to see the solution to all of the problems from the moment that the murder occurred which was rather disconcerting.