Incredibly, unbelievably, Roman's cousin is marrying the cousin of Rosie Taylor (AKA The Worst Person Who Ever Lived) cousin. Roman can't believe this (as Rosie says: 'How can we be in the same family, we're barely in the same species'). Rosie's parents decide they should go along together and 'make a weekend of it'. Roman's plus one is his best friend Gamble (probably the naughtiest kid in Europe) - and it's the beginning of another big, messy, catastrophic and uproarious adventure for Roman - with Winnebagos, illegal thrash metal festivals and campsite beauty contests all thrown into the mix...