Postwoman Mrs Skorepa, her husband the ambulance driver Mr Skorepa and their eleven-year-old twins Petr and Pavel live in Prague in Malá Strana (Lesser Town), one of the Prague's historical and oldest quarters. The boys are crazy about cars and everything linked to them. They don't share their father's love of classical music. On the other hand, they are crazy about the newly announced scrap yard competition for paper collection. The lottery tickets awarded for every ten kilograms of old paper collected could win them a go-kart.

Martin is an innocent lad from small-town Mlada Boleslav who comes to big-city Prague, hoping to exchange his krona for deutschemarks so that he can visit Germany. A local spiv named Robert obliges Martin, but at an unfair exchange rate. When Martin finds out he was rooked, he plans revenge on Robert ... but then decides to join Robert's gang instead.