Millions of these gnus join forces annually to participate in one huge migration - always with luscious grass in their sights. Roaring, snorting, bucking, continuously reproductive en route, they head west - across the Serengeti from Tanzania to Kenya and back. With a large variety of animals in their wake - friend and foe: zebra families that resemble pale flotsam in a dark ocean amidst the gnu herds; or lions, and hyaenas in hope of their next victims. Along their way, they encounter hippopotami and crocodiles - and all of them embroiled in the cycle of "devour and be devoured". The filmmakers follow the artiodactyls, armed with their cameras and lay in wait on the so-called "birthing meadow". There, in the world's largest maternity room, 250.000 calves will be born within the next three weeks. The journey from there to the pasture regions of Kenya is especially dangerous for young animals - and here the film also illustrates nature's harshness. And then there is the "revenge of the gnus", something that Vita and Rolf Köster have become acquainted with. The two filmmakers gained unusual access to the world's most famous game reserve whilst shooting their film in search of the even-toed animals.