Claire and Mitchell's mother, Dede, drops in for a surprise visit and is determined to make amends with everyone she offended during what has been deemed "the incident" at Jay and Gloria's wedding. Needless to say, no one is thrilled to see her and everything comes to a head when the whole family shows up to dinner at Claire's house.

The guest list for Lily's princess-themed birthday party gets a little out of hand when Mitchell decides to invite his mom, much to Claire's dismay, and disinvite Fizbo, much to Cameron's dismay. Things get even more strange when DeDe shows up with Claire's old high school boyfriend in tow, and Jay and Gloria each turn to their own unique methods of dealing with this gathering of misfits.

Cameron watches Alex and Luke while Phil, Claire and Mitchell deal with Haley's arrest; Jay tries to cut a surprise visit from Dede short, so she doesn't learn about Gloria's pregnancy.

Dede is getting remarried, and Manny convinces the family to take the train up to the wedding. Jay could not be more ecstatic that Dede has moved on for good but his overenthusiasm might come back and bite him later. Claire and Mitchell work on their toast while Phil and Cam geek out over their favorite author, who is also on the train. Luke and Manny go a little girl crazy; Gloria gets stuck in coach; and Alex gets caught up in the romance of the train herself.

Cam is incensed that an anonymous and rude parent robbed him of a precious Lily moment during her recent dance recital. While he and Hayley visit Alex at her coffee shop the next day, he thinks he recognizes the culprit and goes to extremes to uncover her identity, and give her a peace of his mind. Meanwhile, Jay, Claire and Mitch attend a family wedding and unexpectedly run into Dede at the reception. Afraid their parents are going to once again make a scene, Mitch and Claire devise a plan to keep them apart. Finally, Phil and Gloria are on a college tour with Luke and Manny, and have very different ways of getting the boys ready to head out on this new adventure and also learning to let go.

Claire is determined to make up for her less-than-joyful mood at Jay and Gloria’s wedding by throwing their tenth-anniversary party. As part of the festivities, Phil is going to perform a magic trick featuring Gloria appearing out of thin air in her wedding dress; that is if Gloria can still get into it!

When Dede drops in unexpectedly, Mitchell and Cam come to a realization about her effect on their lives; Phil, Luke, Alex and Haley all have different bad news to break to Claire and compete about when to do it, the tiny window of time after her monthly spa day when she’s her most relaxed.

It’s another epic Halloween full of costumes, tricks and treats for the Dunphy-Pritchett-Tucker clan as they deal with huge, unexpected news.