Greg and Kim are a little worried when they discover that, thanks to Christine, Logan can read now, because Sam can't. When Kim fears that something might be wrong with Sam, Christine flashes back to when he was seven months old, and she was changing his diaper. And when she turned her back to throw the dirty one out, he rolled off the changing table and landed on his head. In private, Christine confesses to Jimmy what happened, fearful that she's responsible for Sam's stunted development. Jimmy initially doesn't think anything of it, but after Christine succeeds in putting a scare into him, he flashes back to when he was holding Sam and getting ready to watch a sporting event on TV. And when the game started, Jimmy rushed from the kitchen to the living room, and banged the kid's head on the doorway. Christine and Jimmy bring Sam into the guesthouse, and try to get him interested in reading, but when he takes more of an interest bouncing on their bed, Christine wants to tell Kim the truth. Jimmy convinces her to hold off on that, opting instead to cover up the fact that Logan can read. So Christine lies to Kim, and makes her believe that Logan was faking it. But after Kim mentions to Christine that she was thinking of taking Sam to a therapist -- and called it off because she believed Logan can't read -- Christine tells Jimmy that they've lied to them long enough. Although Jimmy would rather tell Kim and Christine would rather tell Greg, Christine gets her way, and after Greg hears what happened, he has his own flashback -- to a time when he dropped a frying pan on Sam's head. Now that all three are in the same boat, Greg decides that they'll hold off on telling Kim, as he wants to take Sam to the doctor first, so they'll know exactly what's wrong. While Sam is being checked out and Greg, Jimmy and Christine are in the waiting room, they get spotted by Kim, who took Emily there for some antibiotics. And when Kim hears that Sam is having a CAT scan, Greg is forced to come clean about the injury, neglecting to state who caused it. So a brokenhearted Kim fills in the blanks, and blurts out that she was responsible. She then has her own flashback to the time when she and Sam were in baby yoga class and she almost bumped Sam's head into a statue. So she turned around, facing the wrong way, and Sam ended up knocking heads with another infant. Kim and the others are all relieved when the doctor comes out with Sam, and tells them that he's fine. But when the doctor gives Sam a green lollipop, and Sam thinks it's red, Greg and Kim worry about that, since Sam knew his colors before. This causes the doctor to have his own flashback -- to a few minutes ago, when he accidentally hit Sam in the head with a light.