When Wendy boasts about being a bridesmaid at her auntie's wedding, Lucy decides to plan the biggest wedding ever. But whom can she find to persuade to get married? When she discovers that Brian and Sophie aren't actually married she sets about planning a grand ceremony. However, her big plans pale into insignificance in comparison to Sophie's, as Sophie turns into a control-freak monster. Meanwhile, Brian puzzles over whether Sophie is his ideal partner, and very soon the two of them not only break off the wedding plans but decide to split up altogether. It's only when they decide that they don't need to follow convention to think of themselves as a normal couple that the family is once again reunited – and celebrates its own form of a wedding, Aliens-style...