With Dermot and Maria's wedding just weeks away, the Brown household is in crisis. Agnes Brown's son Dermot wants to ask his childhood friend Buster to be best man. But Agnes has set her heart on Mark Brown, her eldest son, being Dermot's best man. And Buster is a crook, of whom both the strong-willed Maria and Mrs Brown strongly disapprove. On top of this, Mrs Brown's close friend and neighbour Winnie is distraught. Her husband Jacko has been rushed to hospital and can't possibly afford to pay for the operation he urgently needs. And, needing cash for his wedding, Dermot has allowed himself to get embroiled in one of Buster's stupid- and dodgy - money-making scams. It's time for Mrs Brown to exercise all her diplomatic skills, starting with "accidentally" letting Maria know all about Dermot's best man decision.