When Lewis and Rose Rita explore an abandoned theatre, they discover an unpublished opera score entitled 'The Day of Doom'. Ignoring a strange omen, they show it to their music teacher, who heralds 'The Day of Doom' a masterpiece. Little do they know that the eerie Henry Vanderhelm, the composer's grandson, arrives with a plan to awaken the dead and enslave the world!
Soon, all the adults are enamoured - and enspelled - by Henry Vanderhelm. A mysterious fog descends upon New Zebedee and everyone is trapped inside it. It is up to Lewis and Rose Rita to stop the dead coming back to life.