Seven Wonders #2: Lost in Babylon by Peter Lerangis

Marco disappeared in the first book along with the first loculus. Jack, Cass, and Aly find him in Iraq, and he leads them through an underwater portal to the ancient city of Babylon. They're searching for the second loculus but find citizens from the city stuck in a time warp. A girl named Daria says the king wants them to be his warriors, and she's secretly working for a rebel group. Jack and his friends sneak into a garden protected by soldiers, traps, and deadly creatures in order to steal the second loculus. Unfortunately, they discover the entire city of Babylon, and all of its people, will be destroyed if they take it away.

You must read the first book in the series to fully understand what's going on in this book. The characters continue to develop their powers, although Jack still doesn't understand his strength. This book continues the conflict with the Massa and adds a new twist. The kids are surprised to find out there's a traitor among them. Jack doesn't know who to believe. Will the loculi be used to save their lives, or will they be used for evil purposes?