在这部猫狗互换动画/短片片中,狂风暴雨，电闪雷鸣。在崎岖蜿蜒的山道上，一辆马车左突右撞，惊现非常。在某个拐角处，马车突然甩下一个布口袋。那里是搭车而来的汤姆，他大声抗议马车师傅的粗鲁，不过全然没有用处，于是只得提着皮包赶路。不远处有一个阴森古堡，那里住着邪恶的博士和他的老鼠助手杰瑞。他们发明了一台奇怪的机器，可以将不同动物的身体互换。这时，汤姆辗转来到古堡，他看到安然倚在墙角休息的杰瑞，准备抓住他美食一顿，可是拥有猫的身体的大狗成为杰瑞最忠实的保镖，决不允许汤姆欺负他的朋友。
倒霉的汤姆遭到一连串的打击……
A mad scientist, assisted by Jerry, swaps the brains of a dog and a cat. Tom happens by this castle and is baffled by the dog-like cat's behavior. He keeps trying to convince the cat that it is a cat, but in the absence of a mirror, that proves difficult. He tries to leave, but instead encounters several more mixed-up animals, including a Jerry that's been swapped with Leo the MGM lion.
