Colony Under Siege

A private detective, Doni Doroto, Passenger 763, and his family of four take a vacation aboard the Titans of the Oceans in 2027. The vessel and its crew find themselves on a future Earth, thousands of years in the future, for unknown reasons. Everything is different in this era. Many extraterrestrials from the nearby Andromeda galaxy want humans dead, so people live in generation starships and heavily-defended colonies. An Artificial Super Intelligence, Gaia, teaches Passenger 763, Doni Doroto, about history.
It is Gaia's responsibility to find out what happened to the Passengers. What brought them to the future and why? She speculates about foul play. The Passengers may not be who they claim to be. Is it possible that they are mighty enemies hidden in plain sight?