When Finlay gets a call from The Federal Bureau of Fleas that Fearless French Francois the Fraudulent Flat-Footed Fleeing Flea, or known as his alias, fa fa fa fa fa fa fa fa, has escaped, he calls his family of fugitive flea finders, Felix, Fiona and twins Fergus and Florence to recapture him. They set off on a journey aboard Bentley, the ageing Cairn Terrier, to track down the wanted fleeing flea.