Peter-No-Tail (Pelle Svanslös) is a cat who was born without a tail. He compensates this by studying hard and, much to the dismay of his arch-rival Magnus (Måns), he receives a fancy university degree very few cats in the university town Uppsala, Sweden have obtained. Peter is visited by his American relative Pelle Swanson who invites him to visit his new home country America - in the movie called Americat. There everything is bigger and everything seems possible.
Young graduate student Jane Chase becomes the new assistant to an eccentric zoology professor at the remote home he shares with two brilliant chimpanzees and an elderly orangutan butler named Link. But when one of the chimps is found dead and the professor mysteriously disappears, Link becomes dangerously aggressive towards Jane. Now, the time for “monkey business” is over and the true terror is about to begin.