The planet has been overrun by reptilian super-soldiers. Eight foot tall monsters that could take out a human in one swipe. The surviving humans are forced to retreat below ground. There, they form an army and start preparing to take their planet back. Kade, a young engineer, joins the ranks after narrowly escaping a scrap with a reptile. The monster took his arm, but Kade survived. He works in the builder unit of Los Angeles, developing weapons and armor to withstand the attacks from the reptiles.