This chapter opens with a tap on the door of the hospital. It's a germ that's been trying to get into the red blood cell of a woman named Katherine. Katherine is bleeding from the attack. She's grateful for the help she's received from the white blood cell, which is called a mononuclear cell because it's one of the few cells that can move freely in an organ. The white blood cells are also called macrophages because they're able to take in nutrients from the blood. Katherine thanks the white cells for saving her life. She tells them to get away from her. She also tells them that they'll have to kill all of them every time they try to get in the blood stream. She says that she'll kill them all with her fire power. The crowd runs away, and Katherine is left alone. She wonders what's going on. She can't figure out why there's so much fighting going on between the white cell and the red cell. She asks the crowd if they can laugh at her. They're all laughing at each other, and she feels better.