V
THE ANONYMOUS LETTERS
I
By this time, Barney Cook was a sleuth of several weeks’ experience. Disguised as a newsboy, he had kept watch over a post-box on a street corner until he had succeeded in identifying a blackmailer who was sending threatening letters to a client of the Babbing Bureau. Hidden in the cloak room of a Brooklyn machine shop, he had spied a confidential clerk putting drawings of a new lathe into the overcoat pocket of a confederate who was selling trade secrets to a rival company. He had peddled chewing gum at a subway entrance in Harlem, on the lookout for a cashier who was leading a double life; and he had located the flat in which the suspect concealed himself. Out at
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