I Want You (She's So Heavy) is the sixteenth episode of Season 30.
When a romantic night ends in injury, Marge recovers by taking up kite boarding while Homer bonds with his hallucinated hernia. Lisa attempts to fix her parents' strained relationship by seeking advice from an unlikely source.
Marge and Homer are compelled to go to the Drug and Alcohol Night of Knowledge (D.A.N.K.) at the Springfield Suites Convention Center, so they hire Shauna Chalmers to take care of the children. However, Shauna's boyfriend Jimbo Jones sneaks into the house, where chaos soon ensues. Bored with the D.A.N.K. seminar, Homer and Marge duck out and sneak into the nearby Springfield Wedding Exhibition, using the labels of Dr. and Mrs. Heffernen. Meanwhile, at home, Lisa and Maggie are traumatized by the horror movies that Jimbo is playing, while Bart is hypnotized by Jimbo and Shauna kissing. The children decide to go for a walk, and immediately after they leave, Jimbo and Shauna organize a house party. Ned Flanders sees the children and prepares them for a cup of hot coconut milk. Back at the wedding exhibition, Homer and Marge are forced to improvise the Heffernens' opening speech of the exhibition, "Next Year's Wedding Trends". After the exhibition, Marge and Homer are happy for the time they spent together, but the feeling is almost ruined when Homer finds that the house party is still in progress, so he draws away the partygoers. Homer, still feeling romantic, tries to carry Marge upstairs. At the top, something breaks and Homer and Marge fall down the stairs. At the hospital, it is discovered that Marge sprained her ankle and Homer developed an inguinal hernia from the accident. Back at home, the side effects of Homer's medication make him hallucinate his hernia, now called Wallace (Wallace Shawn), who appears to Homer as a small man. The next day, at Springfield Physical Therapy, Marge is trained by a New Zealand therapist named Nigel, who invites her to learn kite-surfing. Wallace convinces Homer to avoid exercising and a trip to the beach with Marge, causing a rift.
The next day, Marge is visibly disappointed when Homer uses his injury to get out of taking care of the children, so she tells him to call Selma and Patty to help out. They, in turn, drive Homer to the woods and abandon him while he is asleep. Meanwhile in the park, Lisa, without another couple to turn to, asks Jimbo and Shauna for advice, who tell her that Homer and Marge should find common interests. Back at home, Lisa uses this strategy to convince Homer to take the children to the beach under the pretense of a school project. Wallace tries to dissuade Homer from going, but Maggie, who inexplicably can see and hear Wallace, spits her pacifier at and slaps the personified hernia. On the beach, Homer jokes about the weight of Chief Wiggum and decides to join Marge's kite-surfing. Wallace again tries to stop Homer from joining Marge, but is trapped in a pail by Maggie. Homer and Marge then reconcile, but the wind blows their kites in a wind farm where they receive new injuries.
At the Springfield Police Station, Marge discovers from Chief Wiggum that Nigel is really a Russian spy named Dimitri, who was trying to spy on the Springfield Nuclear Power Plant. Wiggum, wearing a Homer disguise and aided by several federal agents, arrests Dimitri.
In the epilogue, a trailer plays for a spy movie called "Mission: Simpossible" starring Wallace the hernia while a pastiche of the theme of Mission: Impossible plays.