Leonard enter the maintenance tunnels to investigate but Peter and Leonard get stuck and send Josh for help. Susan encounters what appears to be a shadowy man in a trench coat on a train platform. As she approaches it, the figure unfolds into an insect the size of a human being. The creature abducts Susan and carries her into the tunnels. Meanwhile, Josh finds a way out but is found by a Judas and killed. Manny also enters the tunnels in search of Chuy and comes across Susan, whom he rescues along with Peter and Leonard, and they barricade themselves inside a train car. Susan surmises that the Judas breed's accelerated metabolism has allowed them to reproduce at a similarly accelerated rate, causing them to evolve over tens of thousands of generations within only three years, developing lungs, allowing increased size, and the ability to mimic their human prey. The group formulates a plan to get the car moving: using the remains of a dead bug to mask their scent as they work Peter will switch the power on, and Manny will switch the tracks. Susan projects that the Judas will spread throughout the tunnels and overrun the city unless they are able to kill the colony's single fertile male. While trying to reach the track switches, Manny finds Chuy who has managed to survive due to his imitating the clicking noises the bugs use for communication, but before they can escape Manny is killed by the male Judas. Susan, realizing Manny has been gone too long, goes in search of him but finds only Chuy. Leonard's injured leg starts bleeding heavily and knowing the smell will only incite the creatures and endanger the group, he creates a diversion that allows the others to get away, before being killed. Peter finds a dumbwaiter and puts Susan and Chuy in it, but stays behind to destroy the breed for good. He is chased into a room where hundreds are nesting and blows them all up by setting fire to a loose gas pipe, before diving underwater to safety. The male Judas however escapes the blast and goes after Chuy but is distracted by Susan, who lures it into the path of an oncoming train, which runs over it. The two successfully make it to the surface, with Susan assuming that Peter had died in the blast. She then sees what appears