The Mystery of the Yellow Room. Gaston Leroux. Wordsworth Editions (1907)

A classic locked room mystery, gripping and highly entertaining. A young woman is violently assaulted and left for dead in a room that has no windows and has been locked from the inside. When the door is broken open the only person in the room is the victim, how could it have happened? Both police detective Fredric Larsen and a young reporter Joseph  Roulteabille are determined to find out. Roulteabille is an extraordinary man, strongly observant and gifted with a powerful logical, deductive talent he sets about resolving the mystery. The story twists and turns in a very happy way, the plot drives with great force and leads to a deeply satisfying conclusion.
One of the major structural problems with a locked room mystery is the importance of the central plot mechanics, it has to be carefully engineered so that the unlocking of the mystery is both credible and satisfying. Balancing this requirement with a cast who are more than mere putters to the plot is a very difficult task, Gaston Lereroux manages it with a flourish. The cast are very engaging and their actions never feel like plot requirements. Indeed one of the great pleasures of the book is the way they are revealed to have driven the plot rather than the reverse.
Gaston Leroux uses a potentially tired formula in the book, having the story narrated by Roulteabille's friend Sinclair, who is very muxh a Watson to Roulteabille's Holmes. Structurally this is effective as it keeps the mystery alive as we see it from Sinclair's view and he is baffled by it, dramatically it works because Sinclair is an engaging and thoughtful character. Roulteabille is much more palatable by being filtered through the friendly eyes of Sinclair than he is in undiluted form. The section in the book taken directly from his notes is effective because it is limited. The human tangle that lies at the heart of the plot is carefully and subtly set up by the author, the impossibility of the events that occur is a generous challenge to the reader.
Any locked room mystery is going to stand or fall by the quality of the central mystery, how did it happen and will the explanation do more than explain the mechanics, will it be fair? In this case the conclusion is breathtaking, both bold and credible, it takes the threads laid in the story and weaves a stunning picture out of them. A great crime story.