Animated short sequel to the 2009 film 'Monsters vs Aliens'. As Susan (voice of Reese Witherspoon) and her monster friends get ready for Halloween, a mysterious slimey substance is dropped onto a pumpkin field by an unidentified flying object. When Susan and her team - who now work for the US government - are sent to investigate the unusual sighting, they discover that the pumpkins are not actually pumpkins anymore; they are mutant aliens with a plan to assume control of planet Earth. Can Susan work out the aliens' plan before it's too late? The all-star voice cast also includes Seth Rogen, Hugh Laurie, Kiefer Sutherland and Will Arnett.