In the Swiss Jura Mountains sits one of the largest known ant societies on Earth, a supercolony of wood ants spread across hundreds of interconnected nests. David Attenborough travels there to examine how a billion individual insects function as something closer to a single organism than a collection of colonies. Close-up photography follows workers hauling pine needles many times their own body weight, tending aphid herds for honeydew, and defending territory with coordinated chemical signaling. Scientists studying the supercolony explain how the ants avoid the infighting that usually breaks out between separate nests, and how the network manages to keep expanding without any central control directing it. The film moves between wide shots of the forest floor, thick with ant traffic, and macro footage that turns individual mandibles and antennae into visible detail. Attenborough's narration keeps returning to the same question the researchers are chasing: what allows a population this large to cooperate rather than collapse into competition.