Irresponsible drunk Hubert (Pete Postlethwaite) stumbles home from a night at the pub and wakes up transformed into a rat. His wife, Conchita (Imelda Staunton), and his children -- son Pius (Andrew Lovern) and daughter Marietta (Kerry Condon) -- don't know quite what to do with their rodent patriarch, but they start to like him better this way. Soon, a smooth-talking ghostwriter (David Wilmot) convinces them to write a book on their experiences and make Hubert a local celebrity.