Danny O'Neill is a bomb disposal expert assigned to a case where terrorists have developed an "invisible" liquid explosive which is activated within the human body.

81-year-old millionaire Jack Watson switches bodies with his 18-year-old grandson David, leading the two to experience life on opposite ends of the age spectrum. But when David, trapped in Jack's aged body, ends up in a coma, his grandfather must use his meager knowledge of the youth to prevent his family from pulling the plug.

A woman is simultaneously framed for the murder of her husband and terrorized by the deranged woman who actually killed him.