The episode starts with a young man knocking on his father's door asking how "it" was. The man responds by saying it was his mother's funeral. The son says he has his cell number but the father tells him it only works if you answer it. The father leaves the son standing in the doorway but then collapses and cannot breathe.
At the hospital, Dr. Murphy arrives for work on time, shocking Dr. Melendez. He answers Melendez sarcastic question about being late with sarcasm, showing he is starting to understand more social cues.
Dr. Melendez and his team are consulting on patient with severe anaphylaxis. It is unusual for the surgery team but the man, who we learn is the father from the opening scene, is having severe abdominal pain.
Shaun sees a young boy in the ER who looks just like his deceased younger brother Steve.
Drs. Jared Kalu and Claire Browne tell Melendez that the pancreas of the father is enlarged. They say he may have pancreatitis. Dr. Melendez disagrees
Dr. Murphy works with the young boy who has broken his arm. The boy says he tripped and fell, which caused his arm to break. Dr. Murphy says he expected it to happen with a more serious accident. Dr. Murphy notices the boy, Evan, has involuntary eye movement and asks if he hit his head. He orders a CT scan on the boy's head.
Dr. Glassman enters the ER and asks Shaun if he is getting sleep. Then, Glassman notices the young boy who looks like Steve. He asks Shaun if it freaks him out and Shaun says no because he is not Steve.
The son sits in his father's hospital room and tells him why he missed his mother's funeral. He says he fell in love in Thailand with a woman who was very sick and he couldn't leave her. The father believes his son is lying.
Drs. Kalu and Browne come in the room at that moment to discuss the CT scan. There is a lesion on the man's pancreas that they need to biopsy. It could be cancer.
Evan is having a CT scan and talking to Shaun through a speaker. He says he's had 2 others before so he knows how it works. Shaun tells him he has autism and social cues and jokes are difficult. Evan says he used to know a boy with autism but he died.
Shaun asks why Evan has had CT scans, and the boy says his parents have nosophobia.
In a flashback, we see Steve reading the dictionary. Back in the present, Evan says he likes to read the dictionary. He asks Shaun if he has a boyfriend or girlfriend, and Shaun says he likes Lea, his neighbor.
Melendez storms into the room and is mad that Shaun is running the CT scan. When Shaun tells him that the young boy has a brain tumor behind the inner ear that affects his balance, he is no longer upset with Shaun.
Shaun tells the parents and they say they know that he has stage 4 osteosarcoma and that he does not know about his cancer. They don't want Evan to know he is going to die.
In the cafeteria, Shaun and Glassman eat lunch and discuss Evan. Shaun asks if Evan has the right to know the truth about his diagnosis. Glassman explains that since he is a minor, they need to follow the parents' wishes. Shaun doesn't understand, and Glassman asks if Steve would want to know truth.
In a flashback, Steve is mad at his dad because he wouldn't let Steve look at his birthday present that he found in the closet. Young Steve does not like secrets so Shaun tells him what the present is. Steve is happy that Shaun told him. In present day, Shaun tells Glassman that Steve would want to know the truth.
Shaun goes to Claire and says he needs her to lie for him.
The son of the sick father goes to Jared to ask if his father is dying. Jared says they don't know yet. The son says his dad is a good guy but they've never been on the same page and that they're both useless without his mother alive. Jared encourages him to talk to his dad.
In Evan's room, Browne tells the young boy that he needs pins in his arm for the break and that Shaun asked her for a second opinion.
Claire and Jared do a biopsy of the lesion on the father's pancreas. They discuss how Shaun and the son came to each of them for help. During the procedure, the father goes into anaphylactic shock.
Evan asks Shaun what's up with Dr. Browne. Evan thinks she is Lea, and Shaun says Claire is his colleague. Evan says he looks at her like he likes her.
Evan tells Shaun that Shaun is a bad liar. Shaun asks Evan how he knows when he needs to lie. Evan tells him if someone doesn't need to know something, he can lie through his teeth. Shaun asks what to do if someone needs to know the truth but it will hurt them. Evan ponders that and says some can handle it and some can't. He tells Shaun that he needs to tell the truth in those situations.
So, Shaun tells him he has cancer. Evan says he knows. He figured out his parents were lying to him and googled his symptoms. He tells Shaun it's okay and that he's not scared of dying. Evan says he doesn't believe in God but believes that it's all random and when life is over, it's just over.
Evan changes the subject and asks Shaun how he met Lea. Shaun tells him and they begin to bond some more.
Jared and Claire tell Melendez that the father had a cyst. He's allergic to something in that cyst and the cyst ruptured during the procedure, causing the anaphylaxis.
Claire and Shaun sit in the cafeteria at opposite tables working. Claire is on her laptop while Shaun is trying to figure out how he can help Evan. The two doctors have conversation about death. Then, Claire discovers something on her laptop and runs out of the room.
Jared and Claire discover more cysts, including one in brain. Claire says the cysts have tapeworms in them, which the father is allergic to.
Jared goes to Glassman because he used to be a neurosurgeon. They will need to surgically remove the cysts in his body to get rid of cysts.
Shaun sits in the on call room surrounded by charts and books trying to figure out something for Evan. He reads the words "mild rash" on his chart and yells out that Evan doesn't have cancer.
The next morning, Dr. Melendez pulls into hospital parking lot while listening to loud music. Shaun is waiting for him in his parking spot and says it isn't cancer. Melendez asks about the biopsies. Shaun says they were positive for osteosarcoma. Melendez reminds Shaun that there is only a point-three-percent chance that they're false positives. Melendez says he can't tell the parents and get their hopes up.
Shaun goes to Glassman and asks him how he can test the boy without telling the parents. Glassman says it's an ethics violation but tells him how to do it anyway so he won't get into trouble.
Jared and the father have a conversation about the man's family business and how his son wouldn't take over. Jared shares his own story about his father wanting him to be in his family's business. Jared explains that he wanted to be his own person.
The father says he and his son used to be inseparable but grew apart as his son grew up. The man says he is grateful his son was at least close with his mother. The father cries over his wife and how he lost both her and his son when she died. Jared says his back back and that the father needs to let go of his grudge.
In Evan's room, Shaun is preparing to give Evan a local anesthetic. Evan asks why and Shaun tells him the lie that Glassman told him. Evan says he is lying and asks Shaun what he is doing. Shaun tells him it might not be cancer and tells the boy not to tell his parents. Evan agrees and tells Shaun to do it before his parents get back.
Evan's parents walk in as Shaun is about to start the procedure. They ask Shaun what he is doing, and Evan says he's giving him pain killers. Shaun says that lie doesn't make sense and tells the parents the truth. Evan's parents are mad that Shaun told Evan he had cancer and try kicking him out of the room.
Then, Evan starts coughing up blood and needs surgery. Shaun wants to assist Melendez with the surgery on Evan but Melendez tells Shaun he is too close to the case. Melendez has Claire scrub in instead.
Shaun and Aaron watch the surgery from above. Shaun asks Glassman if he's in trouble. Glassman says yes, unless he is right. Shaun says the parents shouldn't be upset if he's wrong because they know it's highly unlikely.
Jared talks to the son. He tells him to tell his father the truth before the brain surgery.
Jared wheels the father to surgery, and the son stops them to tell him the truth. His girlfriend wasn't sick. His girlfriend dumped him and he ran away to Thailand because he didn't think he could fill his father's shoes in the family business. He says he proved himself right. The father nods to Jared to continue wheeling him into surgery.
Melendez and Claire work together to fix Evan's embolism that caused him to cough up blood. Claire stops when they go to close him up to show Melendez something.
In the waiting room, Shaun is waiting for news on Evan on opposite side of the room from his parents.
In a flashback, Steve and Shaun are celebrating Steve's birthday on the bus. Shaun gives him a card and a copy of To Kill a Mockingbird. Steve is happy.
Back in the present, Melendez walks into the waiting room. He tells Evan's parents that he is doing fine and they repaired the embolism. Unfortunately, Evan had lesions on his ribs, meaning the osteosarcoma has spread into his chest cavity. The parents are devastated and so is Shaun.
In the father's surgery to remove the cyst on his brain, Glassman is scrubbed in for the first time on the series. Glassman removes the cyst from his brain but they have three more cysts to get.
Back in Evan's room, his parents wake him up and don't tell him about the cancer spreading. They tell him that he will be fine. The parents try to tell him that Shaun didn't know what he was talking about, but Evan tells them he's known for a long time about the cancer.
Shaun watches from the hall while Evan is saying he won't be alone when he dies because his family members will be there.
After his father's surgery, the son talks to his father about his time in Thailand. He breaks down and says he misses his mom. The father is visibly upset but reaches out to hold his hand so they can grieve together for the woman they both loved.
Shaun watches Evan lying in hospital bed. In a quick flashback, young Shaun stands over Steve in a similar fashion after when he fell off the train.
In the present day, Evan thanks Shaun for everything. Shaun asks him for a favor. He wants to read Evan something from To Kill a Mockingbird.
In a flashback, young Shaun stands on the bus distraught after his brother's funeral. He picks up To Kill a Mockingbird and finds a bookmark marking the place where his brother left off.
Back in the hospital, Shaun reads To Kill a Mockingbird from where his brother left off. Shaun thanks Evan for letting him read to him. Shaun is visibly emotional and leaves the book with Evan but takes his brother's bookmark and puts it into his pocket.