To fight on the front lines of the immune system, hardworking cells must undergo intense training. Killer T Cell and Helper T Cell are the best of the best now, but back in their academy days they were nothing more than little cells with big dreams and an even bigger rivalry. Meanwhile, some of the trickiest problems turn out to be the most mundane. The common cold proves to be a serious prankster who’s hard to handle, and the usually calm White Blood Cell finds himself dealing with one of the most annoying everyday maladies…acne.