When his parents go on a cruise, eleven year old Jonathan Leech is sent to Goolish to stay with his grandad. When grandad introduces him to Millie (Brown Howl), Monty and their niece Scarlet, he is appalled to find that Scarlet is a young werewolf and that she thinks he must be a vampire, like his grandad! While the others go off for a bite to eat at Dracdonalds, Jonathan vows to escape. Scarlet reappears and points out that that the next bus out of Goolish isn’t until Tuesday.

Next day Jonathan goes to school where his teacher is Mr Cheng. In the noisy playground, he is befriended by new girl Tiffany. They share their mutual revulsion of the Fang Gang and all the dark side creatures who live in Goolish. Tiffany reveals that she’s formed a gang to combat the dark side elements in Goolish and invites Jonathan to their next meeting.

On his way home through the graveyard, Jonathan meets the Fang Gang. They introduce themselves in the song ‘We’re The Fang Gang’. While the other Fang Gang members go about their business, Scarlet sits down and tells Jonathan the truth about the dark side. Werewolves, ghouls and zombies aren’t bad; just different –and very keen on the art of being scary. But Jonathan’s having no part of it. He denies he’s a vampire and runs off. Jonathan meets Tiffany’s friends at the ‘Sprouts Club’ meeting. When it’s time for him to go home they offer him all sorts of useless ‘anti-dark side’ equipment: sprouts, plastic hammer, water pistol etc…

Jonathan thinks he’s got past the graveyard without encountering the Fang Gang when suddenly he’s confronted by… a headless teacher! It’s Mr Cheng, who reveals that he’s a vampire and as in the Chinese vampire stories, one of his powers is the ability to take off his head. The Fang Gang appear and agree to hunt for Mr Cheng’s head. With Mr Cheng they dance their way to school singing ‘When You Want to Get a Head’. Jonathan is inclined to make his excuses. But almost by default, he gets sucked into the activity. Unconsciously, he is one of the Fang Gang – he is where he belongs. However, the head hunt ends in failure and sorrowfully, Mr Cheng leaves.

The Fang Gang find some papier mâché heads. They have a brilliant idea – why not make a papier mâché head for Mr Cheng? The gang give the head to Mr Cheng. He is grateful, but downhearted. He misses his real head – what’s more Ms Goodbody, the ‘zombie’ student teacher he is taking out clubbing that night, is bound to notice.

At school, the class find Mr Cheng’s false head so scary, they are good as gold in class. Ms Goodbody appears- she has Mr Cheng’s real head in a bag. She had taken it for a haircut. At break time. The Fang Gang start playing ‘catch’ with the papier mache head. In horror, Jonathan suddenly realises he’s playing with the Fang Gang! He storms off. Tiffany appears –sees the Fang Gang playing catch with Mr Cheng’s head, screams ‘orribly and faints. The Fang Gang scarper. Jonathan comes back and the Tiffany comes round. She believes The Fang Gang have murdered Mr Cheng and stolen his head –that’s the sort of thing they do. In the song ‘Team up with Me’ she persuades Jonathan to be a vampire slayer with her. She says she’s got a big plan to deal with the dark side creatures. All will be revealed at the next ‘Sprouts Club’ meeting… Jonathan is seriously worried… confused… unhappy…

At the Sprouts Club meeting the ‘bullies’ are introduced. They are revealed as petty-minded, terrified of the dark, and suspicious of anyone who is different. Jonathan understands which side he is really on. He runs off and finds Scarlet practising her howls. They share the duet: ‘Believe in the Moon’. Jonathan tries to warn the Fang Gang about the danger posed by the Sprouts Club, but they won’t listen. The dark and light side have always lived happily together in Goolish. And besides Tiff is a twit. Moreover, they’re suspicious of Jonathan’s motives. He’s not a young vampire, he’s a jelly baby. For the first time in the show- Jonathan doesn’t deny who he is. ‘I am a vampire,’ he says.

It’s midnight: on come the Fang Gang, Jonathan grandad, Mr Cheng etc. They appear to be carrying bodies, but they are in fact replica vampires (with papier mache heads). They lay these in front of the graves. Then they hide behind the gravestones and wait. The Sprouts and bullies appear to do battle. Triumphantly, they ‘slay’ the dummies. Unable to control his excitement, Fang Gang member Gory leaps up with a ‘Yee-hah!’ The Bullies and Sprouts realise they’ve been fooled. Grandad, Mr Cheng and the Fang Gang try to scare the Sprouts and Bullies, but fail. At the front of the stage, Jonathan appears, terrified. Scarlet appears as a wolf and reminds Jonathan that he has just said he ‘believes in the moon’. Jonathan realises that his ‘grown-up fangs’ have appeared. He turns and with Scarlet scares the opposition.

The Sprouts Club and the bullies all faint. Jubilation: even Gory shakes Jonathan’s hand. Grandad announces that there is party for everyone – blood for the grown ups, baked bones on toast for the Fang Gang! Jonathan’s dad appears. The cruise was cancelled owing to food poisoning. Jonathan is in a quandary – he’s found his place, his true friends, but he loves his mum and dad. Mum appears and tells everyone that they have bought a house in Goolish –his dad’s deciding it’s time he rediscovered his vampire roots. Dad, Jonathan and Scarlet sing ‘Believe in the Moon’; then the whole company join in a reprise of ‘We’re The Fang Gang.’