Walter's parents fly in to be with Megan before she passes. Walter doesn't have the best relationships with his parents, and Sylvester struggles to make a good second impression. The Super Fun Guy decor isn't helping.
Soon after they get to the hospital, it goes into lockdown. An infectious fungi is quickly spreading throughout the hospital, and Team Scorpion is trapped inside, separated. Toby is being a doctor and helping diagnose the fungi, and delivering a baby.
It turns out, Sylvester being a germ freak is actually a life saver. He developed a super bacteria that counteracts the fungus. Cabe pulls Walter out of school, and they tackle the situation from outside the hospital.
Meanwhile, Megan's condition is getting worse. She has a seizure and is semi-conscious. All the while, Walter is trapped elsewhere in the hospital.
The team works together to figure out how to distribute Sylvester's super bacteria to everyone in the hospital. Walter's dad joins in, and Happy exposes herself to the fungus in order to make this work.
Walter makes it to Megan just in time to say goodbye, but Megan had a different goodbye in store. She asked Sylvester to send Walter a video after she died. It's a video of her and Walter at the beach back when she was healthy. When Walter goes to grab a blanket, Megan turns to the camera and leaves Walter a touching goodbye message.