While helping her half-sister, the ruler of Genovia, prepare for her royal wedding, Princess Olivia finds herself facing snooty cousins, school, and princess lessons with Grandmeré. Olivia Grace Clarisse Mignonette Harrison still finds it hard to believe that she's a real live PRINCESS OF GENOVIA. Not only does she get to live in an actual palace with her newly discovered family and two fabulous poodles (who all love her and think that she's anything but ordinary!) but she also gets her very own PONY! Of course, things aren't going exactly like she imagined. Her half-sister Mia is very busy learning how to take over the country while trying to plan a wedding and her father is actually getting remarried himself-to Mia's mother!-and spends most of his time "renovating" the summer palace, although Grandmere says he is just hiding from the wedding preparations. Olivia hardly gets to see either of them. Fortunately, Grandmere has her own plans for Mia's wedding, and needs Olivia's help to pull them off. Just when Olivia starts to think that things are going to work out after all, the palace is invaded by a host of new cousins and other royals who all seem to be angry at Olivia (although Grandmere says they are just jealous). As the day of the wedding gets closer and closer, Olivia becomes more and more worried. For such a carefully planned event, it seems like a LOT of things are going wrong... Can Olivia keep this royal wedding from becoming a royal disaster?