Adult Sheldon explains he’s always loved math word problems. He explains how his younger self needed to get from one class to another in under ten minutes. Sheldon times himself as he walks down the street to see if it’s doable. Later, in the kitchen, Sheldon asks Meemaw if there’s a chance he’ll hit puberty in the next few weeks. He can’t see how he’ll make it between classes without a solid dose of testosterone. Mary suggests asking if he can leave class early, but Sheldon says that’s his favorite part: when he corrects his teachers’ mistakes. Meemaw proposes riding his bicycle, but Sheldon doesn’t want his colleagues to see his training wheels.
When Sheldon goes to see Georgie in the garage as he works out, Sheldon says he was hoping Georgie would help him build up his leg muscles to increase his speed. Georgie says if Sheldon doesn’t want people chasing him, he should be less annoying. After Georgie gives him some small hand weights to squat with, Sheldon manages one and then walks out of the garage mid-squat.
When Sheldon goes to see George Sr. who's watching TV with a beer, Sheldon asks if, as a football coach, George uses growth hormone on his players. George points out they lost their last game 63-9, so Sheldon says he should look into human growth hormone and send some his way. With no access to controlled substances, Adult Sheldon says there was only one option left. Sheldon goes to ask Missy to teach him how to ride a bike.
As Sheldon sits on his bicycle, Missy tells him she’s going to run behind him and hold him up as he pedals. After Sheldon starts pedaling, Missy lets go and Sheldon realizes he’s riding the bike all on his own. Things are going great until Sheldon looks up and sees Billy Sparks’ chicken flying at his face. A petrified Sheldon veers off the sidewalk and crashes into a mailbox.
Missy runs into the kitchen to tell George that Sheldon is injured, explaining that a chicken chased him into a mailbox. When George finds Sheldon sitting on the curb nursing his arm, George asks if he’s okay. Sheldon says he wants his mom, but George says he’s got him. After Sheldon says he can’t bend his arm, George decides to take him to the emergency room.
At the hospital, Sheldon is worried as that’s the arm he writes with, the arm he eats with, and the arm he does the Vulcan salute with. A doctor arrives with the X-ray and tells Sheldon it looks like he broke his ulna; two weeks in a cast and he’ll be fine. Sheldon doesn't like the idea of a sweaty, itchy cast. When Mary arrives to check on Sheldon, George says she didn’t need to come down. Mary points out her baby is in the emergency room. With his father, George stresses. Mary blames George for letting Sheldon get injured, but George says he wasn’t there and if anything it was Missy’s fault. And Belinda Sparks’ fault, too, Sheldon interjects.
As Sheldon and Missy sit on the couch, she asks to sign his cast. When Missy points out that’s what kids do, Sheldon doesn’t understand why he’d care what kids do. Missy says it’s so he’d have a cool reminder when this is over, but Sheldon argues it’s a traumatic incident he won’t want to remember. Sheldon fears she’ll write something mean, but Missy says you don’t commit a crime and sign your name. She learned that the hard way.
When George answers the door, Brenda Sparks is there with a plate of food, saying she wanted to check how Sheldon is doing. George says he’ll be fine, accidents happen. Brenda wanted to make sure their insurance will cover this accident. George says if she’s worried about them sending her a bill, don’t be. Brenda says she wasn’t worried, she just wanted to bring some food as a peace offering and promise it will never happen again. When George peeks under the foil, he’s excited to see a plate of fried chicken. His excitement turns to concern as he looks back at Brenda, who says “Never again.”
Back inside, Missy finishes signing Sheldon’s cast. Sheldon is pleased his big-hearted sister didn’t write anything mean, but unfortunately her message contains the wrong “your”. Sheldon is unhappy that she defaced his cast with a grammatical error, but Missy tells him that’s “your problem. Y-o-u-r.” Later, Sheldon goes to Georgie’s room to ask him for advice on being left-handed. Georgie admits it’s hard to cut things with scissors, but Sheldon’s not worried as his mom handles most of his cutting needs. Georgie says it makes shaking hands difficult, but Sheldon says he doesn’t do that as it’s disgusting. Georgie realizes it makes it harder to drive as the gearbox is on the wrong side, but Sheldon points out he isn’t old enough to drive anyway. Sheldon doesn’t think being left-handed sounds that bad and can’t see why Georgie is always complaining about it.
At the dinner table, Mary tells Sheldon she cut his food up into small chunks. Georgie wonders why she doesn’t chew it for him and spit it in his mouth. After George and Georgie help Sheldon with his mittens, Mary says grace and prays for Sheldon’s arm to be blessed and heal quickly. When Georgie tells a gross story about his friend who got a leg cast off, Mary asks if they can just eat. After Georgie says the chicken is good, George tells them Mrs. Sparks made it.
Later that night, as Sheldon sits with his parents in the den, Sheldon says he’s going to the bathroom for the first time. Mary offers to help but Sheldon says he’ll be fine as it’s just a number one. After he goes inside the bathroom, Sheldon calls for his mother as he can’t get his zipper down. Adult Sheldon explains that he’s not saying he and his mother had a codependent relationship, but she did have a tendency to baby him and, boy howdy, was he okay with that. Mary helps Sheldon brush his teeth and floss; then wraps his arm in saran-wrap so he can get a shower. Mary sits in the bathroom as Sheldon showers, handing him a washcloth and a bar of soap, and dispensing baby shampoo. Later, Mary reads Sheldon a physics book as he dozes off.
Sheldon has a dream about riding his bicycle again where his discarded training wheels adopt Mary’s voice and tell him he needs to put them back on… forever. As Mary sits by Sheldon’s side and reads the book, Sheldon talks in his sleep, muttering “Mom’s my training wheels. I can’t have training wheels.”
When Mary returns to the den, George asks if everything’s okay. Mary says she’s not sure. She explains Sheldon was mumbling in his sleep about her being his training wheels. When Mary wonders what that means, George says training wheels are for little kids, and maybe Sheldon doesn’t want to be a little kid anymore. Mary questions what that has to do with her. George says she’s made it her mission to hold him up. Mary asks George what he’s saying here: that she is wrong to love and protect her son? That Sheldon doesn’t need a mother to keep an eye on him? George isn’t saying that, and would never say that. Mary says “All right, then” and leaves in a huff.
When Mary goes to talk to Meemaw in her kitchen, Mary asks if she had a hard time when her kids started being independent. Meemaw says she’ll let her know - after all, one of her kids is in her kitchen whining about something. After Mary asks her mother to be helpful, Meemaw admits watching your kids grow up is hard, but a little shot of bourbon in her coffee helps. Meemaw tells Mary she’s not even at the worst of it yet - her kids are gonna move out, move to another city, maybe even get knocked up by their dumb boyfriend. Meemaw admits it’s hard being a parent, but if you do it right, they don't need you. Mary doesn’t like the sound of that. She gets it, but she doesn’t like the sound of it.
As Sheldon recites a series of names, Missy asks what he’s doing. Sheldon explains he’s naming winners of the Nobel prize in physics to keep himself from scratching under his itchy cast. When Sheldon says he needs his mom to sing “Soft Kitty” to him, Missy accuses him of being a baby again. Missy points to Sheldon’s poster of Stephen Hawking and says he’s in a wheelchair, but you don’t hear him whining about it in his robotic voice. Sheldon determines both he and Hawking are great minds who faced physical adversity, and since Hawking didn’t let it stop him, he’s not going to let this cast stop him. Sheldon sings Soft Kitty to himself.
The next morning, Sheldon is pleased with himself as he wakes up and realizes he slept through the night. Missy is less than eager to hear about it at 6:14, saying this is why people hate Sheldon. Adult Sheldon says his sister’s grumpiness didn’t dampen his spirits. Determined to take care of himself, Sheldon single handedly goes to the bathroom, opens a jar of jelly for his sandwich. Later that morning, Sheldon raises his hand in bible study class to answer Pastor Jeff’s question about how God touched their lives this week. Sheldon insists He didn’t as He doesn’t exist.
Later, Sheldon takes a moment to reflect on the last two weeks as he takes a bath with his cast covered in Saran wrap. Sheldon realizes Missy was right and he might want to remember this period, so he asks George, Georgie, Meemaw, Mary and Billy to sign his cast.
After Sheldon gets his cast off, he realizes he has unfinished business and gets back to riding his bicycle, this time without Missy’s help. It would take more than a chicken or a broken bone to scare him. It would take a brown beast named Scraps. Adult Sheldon explains he rode his bike for 11 miles that day as the dog chased him.