Trouble seems to follow Cassidy Blake wherever she goes, especially now that she is in Paris. Cass and her best friend Jacob, who happens to be a ghost, are visiting the beautiful city while her parents film an episode of their paranormal television show. While eating delicious pastries and visiting the Eiffel Tower is a lot of fun, there is a very real danger lurking just beneath the city streets. Deep in the creepy, twisting underground Catacombs, Cass accidentally awakens a terrifyingly strong spirit that is unlike anything she has ever faced. Now, she must rely on her rapidly growing skills as a ghost hunter to fix her huge mistake. Cass has to turn to both old friends and brand-new allies to unravel a dark historical mystery before time completely runs out. The angry spirit is getting stronger by the minute, and if Cass fails to stop it, the chaotic force could haunt the city of Paris forever. Get ready for a spooky, heart-pounding adventure filled with eerie underground secrets and unbreakable friendships.