Princess in Disguise — E.D. Baker

With the help of family and friends, Annie and Liam's wedding day looks as if it's going to be perfect until everything starts to go wrong. Liam's father doesn't show up, nor do the magic-wielding guests. Members of the wedding party come down with strange afflictions, Annie's gown is ruined, a storm floods the castle grounds, and an unknown king lays siege to the castle. Queen Karolina decides that they need the help of her fairy godmother, Moonbeam, but a pea-soup fog keeps the messengers from leaving. Only Annie and Liam can get past the magical fog to find Moonbeam, but even after they find her, it's up to them to discover who cast the spells that ruined the wedding, and why the unknown king wants to conquer Treecrest.