Fort Brazos

The city of Fort Brazos and the nearby Joint Reserve military base have been abducted and deposited by forces unknown inside a vast, hollow, 3,900 mile-long cylindrical world. Their homes and businesses all seem the same, but of the over 100,000 population, over 5,000 never wake up at all.  The new world has a diverse ecosphere with multiple continents and oceans, and no visible sign of any other cities or structures or people.