As many readers already know, Judge Dee was a real magistrate who lived in ancient China from 630 A.D. to 700 A.D.; he is also the central detective in a large series of crime novels and short fiction by Dutch diplomat-author Robert Van Gulik (1910-1967).
THE CHINESE MAZE MURDERS (1951 in Japanese; 1953 in Chinese; 1957 in English) displays Judge Dee's talents and abilities very effectively. From the book's beginning, Dee must cope with a local tyrant who has usurped power in the border city Dee has been assigned to, and in later portions of the book a barbarian army threatens to attack this city. Of the three criminal cases that Dee solves, one is a "locked room murder," one is about a painting with a hidden meaning, and the final one concerns the beheaded corpse of a beautiful young woman. In my view, the last case is the weakest of the three, but it involves a family that Judge Dee had been merciful to in the beginning of the novel and has a rather touching concluding scene.
If I were giving this novel a letter grade, it would be a very strong "B+".
P.S. Many editions of THE CHINESE MAZE MURDERS contain a Foreword explaining how Van Gulik came to write that book and a Postscript about historical and literary factors of the book, including the sources he borrowed his plots from. Often, they also have more than a dozen illustrations drawn in a Ming-period style by the author.