A habitual late night stroll down Markendale Square plunges Viner into the middle of things most mysterious and most perplexing. A murder, an imposter, secret papers, all combine to mystify even the police themselves. Is Hyde as innocent of the crime as he claims? What is the clue of the veiled woman and the diamond ring? Things are not what they seem to be and how can Viner prove the man’s innocence? (Summary by Kehinde)