"The Last Hour Between Worlds" by Melissa Caruso is a fast-paced interdimensional fantasy novel that takes place in a city-state called Acantis. The protagonist, Kem Thorne, is a Hound responsible for investigating murders and finding lost children in the Echo layers, alternate realms that become increasingly dangerous the deeper they go. When Kem attends a New Year's party, the guests are poisoned and the mansion falls into Echo 1. Kem must team up with her nemesis, Rika Nonesuch, to escape before midnight. The novel combines action, worldbuilding, and eccentric characters in a captivating way. [Extracted from the article]