The Eternal City (The Castleton Series) (Volume 5) 2nd edition

Seven generations from now an island rises out of the ocean and archaeologists are stunned to find a ruined city. Chaz Newcomb and his team arrive to dig but are forced to abandon their work when all but he fall into a mysterious trace. This leaves only one way to identify the city: go back in time. Once again, the Auckland?s and the CT 9225?s crews combine their efforts. Their quest takes them to the dawn of humanity, where they find the city, inhabited by an unknown species of humans with amazing technology. The citizens are in a trance, all but Carolus Nukium and the city?s three leaders, a set of triplets that call themselves the Triumvirate. When the city sinks below the sea the Triumvirate escapes. The crews pursue them with no idea of the price they are about to pay.