两个青少年注意到同学们突然发生了变化。没有人能够解释这种类似僵尸的行为。在一个看不见的外星生物的指令下，他们对违规者施以无情的暴力惩罚。。Clare Balding and Steve Leonard join teams of pioneering vets around the world who are using the most cutting-edge techniques, often adapted from human medicine, to save the lives of animals.。