Lies and Whispers
On this week's episode of Fringe, "Through the Looking Glass and What Walter Found There," Peter continues to grieve Etta by watching one of her final holograms over and over in familiar surroundings. Olivia discovers him and joins in the sad ceremony and they decide mutual support is imperative to healing. Peter lies about the hole on the back of his neck and tells Olivia it's just a little scratch from his skirmish with the Observers. She buys his story without ever looking at the wound.
Walter retrieves another tape from the amber and sees a familiar locale in Boston. He immediately leaves by himself to investigate. Upon arrival, he's told the apartment he's seeking has been condemned for 20 years. He trudges through the rubble and finds the apartment. He recalls the pattern for entry into the parallel universe, walks it off on the floor and easily slips down through the floor.
When Astrid, Walter and Olivia discover Walter's absence, they go after him. They track him down by the tape he left behind. The tape gives them more detailed info as they draw closer to Walter, and they are able to decipher the code and enter the same universe as Walter. They ponder why he would go off alone.