Lucy returns to the pulpit after having a miscarriage over the summer and has a meltdown. Meanwhile, Martin attempts to get back with Sandy, who decides she wants to be a minister.
Cooking causes relationship woes when Martin misinterprets Kevin's suggestion to make dinner for Sandy, and Lucy thinks Kevin doesn't want her any more because he stopped preparing meals for her. Meanwhile, Eric is mistaken for the twins' grandfather by their new teacher, who then flirts with him.
Eric has a bad day that only gets worse when he loses Happy and has a run-in with the twins' teacher, but a stop at the hospital to visit a sick patient changes his mood.
Eric decides to homeschool the twins in order to avoid their teacher but keeps the decision a secret, rousing suspicion in Lucy, who tries to figure out what is going on by snooping around the house.
Eric has a full house of displaced teens who don't know what to do next for themselves, but seem to know more than they should about his personal problems.
Eric refuses to tell Annie about his diagnosis despite the rumors cropping up about his condition. Elsewhere, Lucy babysits for Sandy and decides it is time to try again for another child.
Lucy has her hands full dealing with the teens and Sandy while Eric and Annie are away, but the most trouble comes from Ruthie, who selfishly refuses to leave Scotland to be with the family.
Sandy agrees to marry Martin, but only to get out of seeing another boy; Kevin tries to help a teen with her spur-of-the-moment marriage to a soldier; and Annie tries to persuade Ruthie to return home.
Ruthie causes trouble at the airport on the return trip from Scotland. At home, Lucy tries to provide counseling for her flock, who are all concerned about Eric. But they're also worried about Lucy, who seems to be holding up too well. Meanwhile, the teens prepare a welcome-home surprise for the Camdens that involves an interesting list of props.
Eric's day starts with some brutal honesty for parishioners who go to him for counseling. He then receives an early holiday gift from Ruthie, but he is more excited about discovering she has fallen for someone and he approves of her choice.
Eric is late coming home but Annie refuses to look for him, relying on her faith that he is fine, so she continues to decorate the house for Christmas and keeps the rest of the family occupied while waiting for him to arrive.
T-Bone and Ruthie fight over their school-report subject; Annie and Eric argue about his eating habits; and Lucy and Kevin disagree about groceries. But the twins find a simple solution to a complex problem that puts everything into perspective for the bickering couples.
Ruthie thinks she and T-Bone should take their relationship to the next level, but he suspects there is more to her decision and asks Kevin for advice. Meanwhile, Lucy and Eric announce they are attending a church seminar, but they really have a fishing trip planned and their spouses figure it out.
Eric's sermons are too depressing, according to the deacons, who want to attract a younger crowd to the church to add to the coffers; Ruthie insists T-Bone get a driver's license so they can go away for privacy; and Mac (Kyle Searles) gets a job at the movie theater so he can afford an apartment with Jane and Margaret.
Eric's parents show up unexpectedly, leading Eric to fear they found out about his heart condition; Ruthie pressures T-Bone into agreeing to a special Valentine's Day gift: matching tattoos.
Ruthie's sudden interest in religion has Eric and Annie guessing about what she has done, and they set out to discover her secret, but no one is willing to offer any information. It turns out Ruthie isn't the only one with something to hide as the truth is finally revealed.
Ruthie panics when the tiny diamond in the promise ring that T-Bone gave her is missing, and she takes it as a sign that maybe they weren't meant to be together. Meanwhile, Eric and Lucy, separately, see a black bird that they believe is a bad omen, perhaps auguring something tragic for Eric. Jonathan: Nick Zano.
While visiting a small town, Lucy and Kevin learn that the residents need a minister, and Lucy considers heeding the call; Ruthie gets her signals crossed and mistakenly thinks that T-Bone or her parents will pay for her tattoo removal; Margaret tells Mac that she's willing to do his English-class assignment; and Sandy catches Martin in a lie.
T-Bone tells Mac in confidence that he's contemplating ending his relationship with Ruthie, and Mac text-messages Ruthie with the news and copies everyone in T-Bone's address book, including Eric and Annie. Meanwhile, Kevin and Lucy debate the merits of moving to Crossroads so Lucy can lead the church there; and Margaret gets mad at Mac when he turns in her paper as his own.
T-Bone's estranged father (Diedrich Bader) shows up at the Camden house; Kevin tells Lucy that their plans for a second baby mean it's not a good time to consider relocating to Crossroads; T-Bone tells Eric that he is uncertain about ending his relationship with Ruthie, who is spending a lot of time with Martin; and Jonathan proposes to Sandy.
Feeling giddy and energetic, Eric goes to the hospital convinced that his heart condition has changed for the better, and Lucy is frantic with worry as they wait for news. Meanwhile, Ruthie and T-Bone decide to get back together, but their decision is complicated by Martin's revelation to Ruthie that he loves her.
In the series finale, the Colonel sends Eric and Annie a gift---an RV---prompting Eric to talk Annie into taking the family on a trip to see America, and the list of traveling companions grows by the minute. In the middle of the happy madness, Lucy and Kevin make an announcement.