Revolution — Gail R. Delaney

The Areth came to our world in the early years of the 21st Century, proclaiming to be our brethren, our ancestors, our allies.
Decades have passed and the Areth have now infiltrated every part of Earth society: government, medicine, science, even religion. Some say the Areth are our salvation, others say they are our doom.
Retired Earth Force Colonel Nick Tanner doesn't care. He gave up caring years ago. More than once the Areth have cost him everything he loves and holds dear.
Then Doctor Caitlin Montgomery, the woman he has never been able to forget, finds him in his solitude and changes everything.
His son -- the child he was told died twenty-five years before -- is alive and needs him. Nick will do whatever it takes to bring Michael home. He'll lay down his life, if that's the cost to reveal the truth and stop the Areth.
Now, he cares. And if he ever finds the Areth that stole his son from him, she'll pay.