Frank Detomello is a slovenly zoo keeper, and simple father to the only young and bright girl named Shane, who catches a cold right after he swallowed a germ-ridden egg! The inside of his body is known as the "City of Frank". An unlikely hero of a policeman white blood cell, by the name of Osmosis Jones, works as a member of Immunity cell. But with that germ-ridden egg comes a mortal danger: Osmosis discovers Frank has really contracted a villainous and black-hearted deadly virus known as Thrax...