Life's not easy for a workaday cell, and amid all the hustle and bustle it takes to keep the human body going, it can be hard to know who's an enemy and who's a friend. You might think all germs are bad, but it turns out some bacteria aren't just friendly, they're downright essential (not to mention cuddly!) In fact, when an old nemesis returns, it might just be those friendly, cuddly bacteria that help save the day. The saga of life inside you continues!