Red rain falls under the dome and it burns people's skin. Lyle the barber believes they are being tested by God, while Rebecca provides a scientific explanation for the acid rain.
Sam tells Junior that his mother had blackouts too and that sometimes she'd remember if she went back to location where she had them. Junior goes back to the school to see if he remembers.
Joe, Norrie and the mystery girl go to the school to work on a project for Rebecca. They find Junior there. There's internet connection at hte school and James gets a message from his mother. She tells her son that she's alive and Lyle has answers. The signal goes out and it's tracked to the locker. The mystery girl knows the combination.
Joe finds a year book and they determine the mystery girl looks just like the locker's 1988 owner, Melanie Cross.
Rebecca stops the acid rain by clearing algae from a lake.
Rebecca and Jim surveyed the residents to prepare for a purge if it's necessary.