Kevin goes all out to create the perfect romantic setting for Valentine's Day. Lucy doesn't wanna attend because she had him agree not to propose on Valentine's Day. Eric and Annie convince Lucy to go. Kevin invites all the Camdens, his brother Ben and their mom to be there with him when he finally gets down on one knee to propose to Lucy. Meanwhile, Roxanne overhears Chandler practicing his own proposal to her but she asks him to wait so they won't steal Lucy and Kevin's thunder.

When a nasty thunderstorm rolls through the region and threatens to postpone Lucy and Kevin's wedding, everyone scrambles to make it to the church in time. Mary barely catches the last flight in and brings Matt with her. Chandler and Roxanne rush to pick up Ben and his mother who are stranded at the airport in Las Vegas, but tensions run high and a fist fight breaks out; and Matt gives Lucy some very special brotherly advice when she confesses to pre-wedding jitters.

A non-church patron Marie enlists Eric's help in handling her elderly mother, Mrs. Wagner into getting her into a nursing home, but Eric gets a different impression when he finally meets Mrs. Wagner and sees that she doesn't need help and is still very capable. In fact, it turns out Marie may need more help than her mother as she's very unhappy with her life. But things turn out bad later on when Mrs. Wagner ends up in the emergency room due to her stress from her daughter.

Ruthie puts up a fight with Lucy while shopping as she wants to spend the day with Vincent without Annie knowing about it. Ruthie wants to go to a family dinner with Vincent. Although, it inevitably blows up in her face and leads to an interesting conversation with Annie and Lucy in the driveway.

Ben (guest-star Geoff Stults) shows up in Glen Oak to pay Kevin and his new family a visit and makes himself well at home again in the garage apartment. But Kevin is not happy to see his brother as he wanted his mom and hus