The Untime: A Novel of 19th-Century Paris. The Untime, #1

The Untime; a mysterious and dangerous state, beyond our powers of conception. In the Paris of the 1890s, Jules Gauthier, a young journalist, enters the Untime with its discoverer, Professor Lamartine. What they find there could be the end of our Universe as we know it. When Lamartine disappears mysteriously, Gauthier, together with Agathe, Lamartine's daughter, and Lamartine's rival, Professor Schneider, must brave the terrors of the Untime, journeying through time and space.