Jerry is awakened from a nightmare by a knock on the door: someone has left a foundling in a walnut shell with a note, giving his name as Nibbles and saying he needs lots of milk. Fortunately, there's a dish handy, but it's next to Tom. Nibbles scurries out and dives off Tom's nose, then grabs a whisker for balance, waking Tom up. Jerry grabs him just in time and they hide under the milk. Tom laps up some milk and gets Nibbles; Jerry rescues him, and they run for the hole. Next, they try a very long straw; Tom catches them and sucks Nibbles through the straw. Much chasing follows, with a pause now and then for some milk. Tom traps Jerry in a milk bottle and chases Nibbles a while; he finally corners Nibbles and spanks him with a flyswatter. Jerry is so enraged he burst out of the milk bottle and lets out a ferocious roar; he grabs Tom by the tail and thoroughly pummels him, then stands over him as Tom feeds Nibbles milk.