"Its Halloween night in Gotham City, and the streets are full of monsters--real ones! Batman is battling a crime spree being carried out by the spookiest villains in town--Scarecrow, Clayface, Solomon Grundy, and Silver Banshee--who are all secretly working for the Joker. The evil mastermind wants to unleash a computer virus that will make all technology cackle and obey his every command! The Joker thinks hes in for a Halloween treat, but Batman has a trick up his sleeve: his pals Green Arrow, Cyborg, Nightwing, and Red Robin are joining him to fight back! Can they save Gotham City before its too late? Find out in this novelization that includes eight pages of full-color stills from the Monster Mayhem Batman animated film..."-- Provided by publisher.