Trainee Secret Agent Oli Biggles is on a mission - to track down an International Criminal Mastermind. Oli's friend Skipjack is also on a mission - to escape being bashed by his old enemy Slugger Stubbins. Dodgy dentist Professor Vladimir Vakloff is on a mission, too - but it's a secret. When all these missions meet at the Summer Fancy Dress Fair - it's trouble!