"Nikki is in the spotlight. A reality TV crew will follow her and her friends for the whole month of March as they record their hit song together. But will the excitement also cause unexpected problems, now that cameras are everywhere Nikki and her friends go?"--

Asked by a Bollywood star for help protecting a valuable ruby, Geronimo Stilton and Hercule Poirat are inadvertently cast in the actress's film in spite of limited acting skills and are horrified when an anonymous thief makes off with the ruby.

Now in Paris with her parents who are filming their TV show about the world's haunted cities, Cassidy Blake (who can see ghosts) and her friend Jacob (who is a ghost) are alert for trouble, especially when the filming takes them into the underground Catacombs, the empire of the dead, where Cassidy accidentally awakens a powerful poltergeist spirit--one whose mystery she must solve before his power in unleashed on the whole city.--