Beware, the Usurpers!  (Paperback, Robert W. Krepps)

The central conflict of the novel revolves around the discovery of a mysterious alien race known as the Usurpers. These beings possess advanced technology and a hostile attitude toward humanity, seeking to conquer and subjugate human colonies throughout the galaxy. As the Usurpers launch their campaign of conquest, humanity faces a desperate struggle for survival. The novel follows a diverse cast of characters, including military leaders, scientists, and ordinary citizens, as they band together to resist the alien invaders and defend their way of life.