David Attenborough is in the Swiss Jura Mountains to discover the secrets of a giant. Beneath his feet lies a vast network of tunnels and chambers, home to a huge empire of ants. It is believed to be one of the largest animal societies in the world, where over a billion ants from rival colonies live in peace. Their harmonious existence breaks many of the rules for both ants and evolution, and raises some important questions. Through winter, spring and into summer, David turns detective to find the answers.

西非撒哈拉沙漠边境，统治族群长达三年之久的黑猩猩戴维面临其他雄性的挑战，为了守住王权，他开始选择结盟。而当遭到围攻后，这位不死的王者又毅然决然踏上夺回王位的复仇之路。南极大陆，数千只帝企鹅爸爸团聚一起，与极其寒冷的永夜作抗争。他们等待新生命的出生，等待 爱人的归来。肯尼亚草原，雌狮查姆竭尽全力守护族群，在巨大的灾难面前，他必须面临生死存亡的考验。津巴布韦国家公园，垂老的三色狼泰特渐感力不从心，她对家族的控制力逐渐减弱，而她的女儿正在崛起，觊觎着母亲的皇位。印度，雌虎拉杰贝拉靠一己之力捕捉猎物，养育四个孩子，但是大自然从不因此对她慈悲半分。