Cath and Si are best friends. Total opposites, alwasy together and both unlucky in love. Cath is scatty, messy and emotionally closed, and Si is impossibly tidy, bitchy and desperate for a men of his own. They live near each other in West Hampstead, close to their other best friends Josh and Lucy - who are married, with a devil-spawn child called Max and a terrifying Swedish nanny, Ingrid...