Having decided on visiting Dr. Crombel in order to gain trust and eliminate the suspicions entangling them, M-21 and M-24 takes the risk. Dr. Crombel, who was also the one in charge of their experiment, is quite surprised to see them and asks about their current conditions. He further commends them to undergo experiments. M-21 and M-24, resolute on hiding their special changes from him, knows that he'll notice their changes if they participate in any experiment. So, M-21 rejects the offer saying that he is afraid. After living so long as an experimental material, he doesn't want to take on another experiment. This convinces Dr. Crombel and he lets them go but tells them to come back a few days later as he'll personally check their conditions. Meanwhile, Mary, Jake and the infected have searched every nook and cranny in Shinwoo's apartment but have found no sign of the owner. So, Mary decides to find out the address of one of the children from M-21 and M-24 and kidnap the one to bring out the others.