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The Wild and Woolly World of Nonlinear Dynamics is the eighteenth episode and season four finale of the American sitcom Young Sheldon. The episode aired on May 13, 2021.[1]


Missy's first heartbreak triggers a series of events that lead the Cooper family to the brink.

Extended Plot[]

The episode starts with Pastor Jeff telling Peg and Mary that his baby son was born. Sheldon is at home in the kitchen with Meemaw on the phone with his parents. Missy comes home sad and walks into the bedroom. Meemaw knocks on her door, but is rebuffed.

At the church, Mary asks Peg to do something to help; Peg tells Mary she is not in charge of her despite being the church secretary. Mary later comes back and says Peg is right; Mary wants to take charge and gets things done. As Peg is doing crosswords, she tells Mary that she likes thinking she is better than everyone.

George comes home and talks to Missy. He says if this is about a boy, there are other boys out there; she retorts saying she solely wants Marcus. George offers to get ice cream but she does not want to do anything. He leaves. Meemaw asks if George got it resolved; George comes back and tells Meemaw that only Mary talks to her.

While George is sitting on the couch reading, Sheldon asks if he can ignore a “Do not enter” sign on the door. He tells Sheldon he cannot ignore it; Sheldon proceeds to go in. Missy is putting toys away and wants to throw them away. The siblings quarrel and it escalates to the point where she wants to take down a poster of Cyndi Lauper, but Sheldon does not want her to take it down. She argues about herself not being the one to tell him not to take down his posters of well known scientists. Sheldon says that she is irritable, compares her IQ to the scientists saying she's stupid, and that her behavior is the reason why she's causing girl problems; she gets mad.

George is sitting outside in the living room when he hear screams. He walks into their room to see Missy having ripped up a picture of Professor Proton. He asks Missy to explain herself, and she goes to her bed crying. Mary comes home and is confused. She realizes she had ripped his picture. She barges into Missy's room and demands that she apologizes for ripping Sheldon's picture; but Missy snaps at her saying that everyone takes Sheldon's side, adding how she hates her family and in a fit of rage, Mary grounds her. In the corridor, George sarcastically said that she did a good job handling the kids. Sheldon walks to Meemaw's house and asks if she can bake cookies. She tells Sheldon to not say that he hates his sister by being more empathetic towards Missy's first heartbreak, and to find a way to forgive her. She also tells Sheldon that since he is older by 2 minutes, he has the brotherly responsibility.

Mary and George argue about arguments, doing stuff for each other, and have a heated argument. While they argue, Missy packs a bag, and exits the household from the window. Georgie comes home and asks if someone died. George confirms no one died but there was some conflict. He is perplexed at what happened that day. Mary tells him that neither of them are cooking so he has to make something for himself to eat. Mary goes to her room and Georgie brings her some soup to make her feel better. Missy walks out on the sidewalk, and hides behind a tree as she sees Sheldon. He finds her and they walk together; he says he is born 2 minutes earlier and has the older brother responsibility. Missy tells them to walk together and leads him to a cabin. At the cabin, Missy reveals it is her favorite place to be just to get away from everyone. They talk and discuss things, including Missy telling Sheldon about how she caught Marcus cheating on her with another girl at the roller rink. Sheldon comforts her. They make a pact betting $1 that in 10 years, she and he will not be sitting there talking about Star Trek.






  • The Word Jumble that Peg is working on is credited to Meagen Brooks, a graphic designer/artist who works on the series.



  • This is the Season finale due to Covid, resulting in a shorter season of 18 episodes, rather than the usual 22
    • Season 3 also had a shortened season, but only by 1 episode as oppose to Season 4's 6 episodes.
  • In this episode we see George Sr. having an encounter with Brenda Sparks. It is possible that this could be one of the affairs that lead to Sheldon walking in on his father.
  • This episode is similar when Sheldon ran away from home in An Entrepreneurialist and a Swat on the Bottom.
  • It is revealed that Sheldon was born two minutes before Missy.
  • This is the first time Missy runs away from home, which could foreshadow her "difficult times" in Season 6.
  • Missy and her mother always had a falling out and Mary punished her again, like last time when she tried to swear.