In the laboratory Vivi-Sec UK, a group of five animals are part of the fourth batch of Project S, an experiment designed to create talking animals.

The animals are given a sophisticated lifestyle in order for them to develop their intellect, living a luxurious life run by computers that something similar to a four-star hotel, unaware they are really part of a laboratory experiment. They have human-like personalities and names, wear specially designed clothes, speak in a pseudo-intellectual fashion, eat gourmet food, drink fine wines, read books and magazines and generally live like humans in luxury. Meanwhile, the other animals outside Project S are tortured with horrific experiments.

The animals in the experiment include

• Philip Masterson-Bowie the horse (voiced by Steve Coogan)
• Niall the rabbit (voiced by Arthur Mathews)
• Winona Matthews the pit bull (voiced by Amelia Bullmore)
• Hugh Gape the monkey (voiced by Kevin Eldon)
• Claire Franchetti the rat (voiced by Julia Davis)
• Mark Andrews the sparrow (also voiced by Steve Coogan)
• Kieron the cat (voiced by Simon Pegg)

A group of animal rights activists break into the laboratory to rescue the animals. Kieron is left behind, having his head removed from the rest of his body and being kept alive by machines. As the other animals are boarded into the activists' truck they don't know what's going on, and are joined by Niall, a rabbit from an earlier batch of Project S which can only speak computer advice.

When one of the animals asks the activists if they will be stopping for a toilet break, they panic and crash the truck into a tree. The animals escape, and go their separate ways. After running into humans who are shocked, and other animals who can't speak like they do, they deduce they have somehow been transported into an alternate reality where only humans can speak and the other animals are enslaved by them.

Meanwhile, Vivi-Sec UK has Kieron's head grafted onto the body of a gorilla and is sent out to assassinate the other animals. Vivi-Sec UK also alerts the media that dangerous talking animals are on the loose.

The animals take shelter in an elderly lady's house, who calls her psychiatrist to tell him that there are talking animals at her house. Believing the elderly lady to have snapped, he has the medics take her away, leaving the animals

• Official site
• Peter Baynham's rebuttal to criticism that animal testing "isn't a suitable subject for comedy."
• Triffic Films site
• BBC - Comedy Guide - I Am Not An Animal
• Slate- A Horse Walks Into a Bar... I Am Not an Animal is a cheerfully sicko social satire from the BBC.