Like The Mystery of the Yellow Room, The Secret of the Night is a Joseph Rouletabille mystery. There've been so many locked-room mysteries since that it's become a subgenre - but there are folks who believe Gaston Leroux invented the form. (We hate assertions like that. Have you noticed how often things turn out to have been invented by monks in the middle ages, or by prehistoric Chinamen, or seventeenth-century Englishmen? - Heavy sigh.)