"The Mystery of the Boule Cabinet" is not a French detective story, insasmuch as the scene is laid right in the heart of New York City; but it is worthy of the best French masters of detective fiction in its audacity of plot, in the logical and at the same time baffling manner in which the clues are unwound, in its astonishing turns and twists, its astounding dénouement, and above all in its wonderful central figure, who is one of the few really great characters in detective fiction.