This episode explores the impact of alpha animals around the park, kicking off with the arrival of a hot new zebra stallion. But will he be able to tame an unruly herd of eight fiercely territorial females? And what will towering giraffe bull Thorn make of this new stud stepping on to his turf? The cheetah family face yet more turmoil as the whole breeding group looks to be in jeopardy now the life of dad Carl hangs in the balance. A suspicious lump on his leg needs to be investigated, but with Carl's life nearing its latter days, an anaesthetic comes with great risk. Kate meets Buster the sea lion, and the lions face their mortal enemy as Jean and Caleb give them a true call of the wild.