This book is a little too much of the period, and the author, even as she breaks new ground with respect to the detective novel, is very much of her time and class and place. The dialogue is stilted and unnatural, with every utterance verging on melodrama, which is typical of popular literature at the time. Interestingly, the detective – not the lawyer, but the actual detective, of whom there is surprisingly little in the story – is much more recognizable, and even foreshadows the “defective detective” trope by giving him a quirk: Gryce does not make eye contact with his interlocutors.
That being said, the mystery has a lot to recommend itself, and despite a few minor contrivances and coincidences, is largely put together in a way that, on re-reading, shows it to be traceable by the attentive reader. There isn’t this tendency that Conan Doyle had, for instance, to have the base his far-fetched but invariably correct deduction on a clue denied to the reader until the end. Gryce works hard for his victory, and he earns the conclusions he comes to.