Guardians of the Sky — Gary Jonas

WE ARE NOT ALONE

When Steve Riley stops for a burger on a road trip, a dying man hands him a file that proves the US government has aliens in captivity.  Before he can even process that information, he's thrown into an ongoing battle between a secret breakaway group within the government, a private organization investigating UFOs, and different contingents of aliens from outer space who have been visiting Earth for millennia, and are on the verge of war.

But what can one man do?  With Men in Black trying to kill him, a private group trying to recruit him, and aliens with their own agenda, Steve must find a way through the intricate web of conspiracies or die trying.