Piper puts together an engagement party for Paige and Henry, but the couple gets cold feet and the wedding is jeopardized. Phoebe notices an odd man following her, and discovers that he is a Cupid. A demon uses Christy to lure the Charmed Ones into attacking The Triad, a move that the sisters think will lead to Leo's return.

Mr. Krupt is the schools new gym teacher and introduces Bart and the kids to BOMBARDMENT! Barts attempt to get back at the new gym teacher results in the destruction of Groundskeeper Willies shack and the family takes him in. Lisa decides to make Willie the focus of her science fair project and tries to turn him into a proper gentleman with surprising results. Meanwhile, Homer has ruined his last pair of blue pants and attempts to generate interest in them so the manufacturer will start making them again.

Drew Lachey and Cheryl Burke are crowned Dancing with the stars champion. Also Mary J. Blige perfroms two of her hit singles and all the celebrity dancers are back to perform one last time.

Because of a past incident at his own prom, where he was lured into a dance with the homecoming queen only to have a pile of pigs dropped on him, Stan wants revenge by showing off that he married a homecoming queen, Francine. A proud Stan accompanies Francine to her reunion, but when they find out that two ballots were lost and that Francine didn't actually win the crown, Stan is devastated. Meanwhile, a dejected Steve is "saved" by a pizza delivery man with a Messianic message.

The case of a female bank teller shot to death in her work in 2000 is reopened when the same bank is robbed again by perpetrators wearing identical masks and equipped with identical weapons as six years earlier.

Meredith and George are experiencing morning-after tension at home and at work and it has the rest of the doctors wondering what's up. Derek and Addison are experiencing their own version of morning-after tension as a result of Mark's visit to Seattle. Bailey, returning the favor that was done for her during the Code Black situation, must treat Addison for a specific feminine problem. Izzie and Alex are making headway in their relationship until Denny Duquette comes back. Soon Alex is not-so-oddly jealous of the attention Izzie is showing to Denny. Someone finds comfort in confiding in a patient who is going through an ordeal of his own. Burke deals with a patient and gets to observe the patient's unstable relationship with his fiance.

Jenny plans a charity event to support Max when they find out he can't pay for the top surgery. Helena takes the girls to a surprise trip to honor Dana in her recovery, and Carmen is still dealing with the aftermath of Shane's ex. Meanwhile, Bette kicks Tina out of the bedroom and tries to find peace in Buddhism. In a recording studio, Kit gets help from unexpected sources -- but is it too much to handle?

Sam encounters his parents again in 1973; he believes that if he keeps his father from running away he will be awoken from his apparent coma. The closer he gets to apprehending his father, the more he hears sounds that tell him he's close to waking up. However, rather than traumatizing his family more by arresting his father, he instead lets him run away. Flashbacks throughout the entire series are revealed to have been from young Sam's memories of this incident.