Pete Postlethwaite is Hubert Flynn, Dublin bread delivery man, who loves his pint of Guinness, his bet on the horses and his wife Conchita, in that order. So when he comes home from the pub one evening and changes into a RAT, Conchita is slow to forgive. Conchita at first resists her family's eccentric plans for Hubert, but when an opportunist ghost-writer knocks on the door and proposes to put their story in a book and then a film of the book and a book of the film and riches beyond her dreams...she is tempted, so setting the stage for a series of bizarre and comical adventures for Hubert the rat and his family.