As the show opened last week, a mental patient was undergoing brain surgery by someone from the other side. While undergoing the surgery, he is discovered and leaves the man with his brain exposed.

The Fringe team comes in and learns that before this apparent surgery, the patient was crazy, but has become completely sane since having his brain opened up. After doing some research, the team finds out that this has happened several times to different patients at different mental facilities, including Walter.

The team comes to understand that all the patients had a piece of brain tissue removed, pieces of tissue that belong to Walter and were being stored in their brains. By the time they figure it out, Walter is drugged and taken by the man from the other side (Newton) and his team. Newton brings Walter to his old home, reinserts the tissue and asks him to remember how he opened the door between the two worlds.

Newton takes off leaving a dying Walter behind. Olivia catches Newton, but she is left with two choices: She could have arrested Newton and gotten answers to all her questions, or she’ll have to let him go to save Walter. Olivia lets Newton go free and runs back to save Walter right in the nick of time.