At long last, Michiel gets to the bottom of what the microbiome means, as Professor Sofia Kirke Forslund-Startceva reveals an uncomfortable truth. Meanwhile, Minerva travels to the lung mountains... Will she find the source of what is causing her sister's illness?

Biopolis - into the microbiome is created by Michiel van Poelgeest for the Max Delbrück Center. Script consulting by Jeff Emtman, additional narration by Colette Kinsella.