AE3803 is rescued from a germ by a mysterious immune cell called Monocyte, who doesn't speak and wears a hazmat suit. Later, the nasal cavity gets invaded by a band of Staphylococcus aureus. Vowing revenge for one of their number who was killed in "Scrape Wound", they combine their bodies into a powerful giant who is able to trap the white blood cells in a net of fibrin. A squad of Monocytes appears and sheds their hazmat suits to reveal that they are Macrophages; Monocytes being one of the many roles they play. The Macrophages easily defeat the invaders. As the white blood cells thank the Macrophages for saving everyone, AE3803 asks one of them how they fit their enormous dresses inside the hazmat suits, but she tells her it is a secret.