In a future where humans are losing trust in robots, Detective Ross Sylibus is sent to Mars after his partner's death at the hands of a robot. On Mars, he gets entangled in a murder case involving a country singer, meeting his tough partner, Armitage. As they investigate a series of female murders, they discover a hidden truth - a new line of robots called Thirds is being targeted by a serial killer. Armitage, who is revealed to be a Third, leads the charge to stop the murderer and protect her kind.