In this episode, Red Blood Cell witnesses Monocyte doing a lot of weird things around the body such as sleeping in a hot spring and hiding behind lamp poles. Suddenly, Staphylococcus aureus (S. aureus) invades the human body to take revenge of her cousin who was killed in episode 2. Neutrophils appear in time to kill them, but the remaining bacteria fuse to form one giant monster that attacks the neutrophils. Just as the neutrophils get overwhelmed, the monocytes arrive and transform into macrophages. The macrophages beat up the S. aureus giant, breaking it off into individual bacteria that run away and get killed. Following this, macrophages and neutrophils thank each other for working together to eliminate S. aureus.

What happens during S. aureus infection and do macrophages really save neutrophils from being overwhelmed? Find out as we dive into S. aureus infection.

In this episode, Killer T Cell trains a group of Naïve T Cells while Helper T Cell and Regulatory T Cell work in the office. However, when Killer T Cell throws Naïve T Cell which hits Helper T Cell, Killer T Cell and Helper T Cell argue with each other. In the meantime, Dendritic Cell tells a story to Naïve T Cells on how Killer T Cell and Helper T Cell met while they were thymocytes in the thymus. While Helper T Cell easily passes the training exercises, Killer T Cell barely manages to keep up. With the advice of Helper T Cell; however, Killer T Cell manages to pass his final exam. Before leaving the thymus, Killer T Cell and Helper T Cell make promises to each other, with the former vowing to get stronger and the latter deciding to become a commander to coordinate other immune cells.

How do T cells really develop in the thymus? Join us as we go inside the thymus to describe what thymocytes go through to become mature T cells.

In this episode, Red Blood Cell, after realising that she is not a junior cell anymore, is determined to deliver oxygen to cells by herself without getting lost or relying on other people. We follow Red Blood Cell’s journey as she travels through the veins and heart to the lungs to drop off the carbon dioxide. Picking up oxygen from the lungs, she then travels downwards through the heart and arteries to deliver oxygen to cells. Unbeknownst to her, Neutrophil follows her, ensuring that she does not get lost, drop her notes or get killed by bacteria. Thanks to Neutrophil, Red Blood Cell manages to safely go around the human body by herself which she talks about to Neutrophil.

How does blood circulation work in real-life? Join us as we learn more about the cardiovascular system and its importance in sustaining cells around the human body.

Over one and a half episodes, Neutrophil, Killer T Cell and NK Cell battle against Cancer Cell. It all starts when, after killing a cancer cell, they are escorted by a normal cell to an abandoned building. Neutrophil and Killer T Cell explore the building, where they find cancer cells endlessly proliferating, not following the normal proliferation program. Meanwhile, NK Cell takes the normal cell aside where she reveals that he is really Cancer Cell. The white blood cells are bombarded by cancer cells and are beaten up by Cancer Cell as the building collapses. They are saved; however, by immune cells brought together by Red Blood Cell to kill the cancer cells, ending the threat.

What is cancer and how does the immune system prevent cancers from growing and spreading? Find out as we delve deeper into the topic of cancer.