The original title for the show was Battleground: Earth, but the producers changed it because it sounded too much like L. Ron Hubbard's novel
They are the Companions. Aliens, come to earth on a mission of peace. Their true mission, the secrets they hide, forever alter humanity. In the struggle for our planet, the battle between these Taelon Companions and the Human Resistance, holds the key to Earths future and the fate of mankind. On EARTH: Final Conflict"
"Three years ago they came, forever altering the future of humanity. William Boone's life has been destroyed. A man caught between two worlds. Assigned protector to the Companions; undercover agent for the Liberation. An alien implanted cyber-virus expands his mind. Controlling a bio-engineered weapon of unprecedented power. William Boone searches for the truth."
The story begins three years after the Taelons arrived on Earth. The Taelons have used their advanced technology to help humanity achieve a better quality of life. However, the North American Taelon Companion, Da'an, is targeted by an assassin while making a speech. Jonathan Doors, a businessman with close ties to the Taelons, is killed while Da'an is unharmed. Da'an is impressed by Police Commander Boone's work in protecting him from the assassination attempt, and offers him a spot as a Taelon Protector, a personal body guard and envoy for a particular Taelon.
Boone politely refuses because he wants to start a family with his wife. Also, deep down, he doesn't trust the Taelons fully. Subsequently, Boone's wife is mysteriously murdered and Boone finds out that Jonathan Doors faked his own death so that he could focus on his resistance movement. Doors believes the Taelons have sinister intentions, and wants to find out their true motives.