As they all head into the lab, Astrid explains that the beeping seems to be repeating in a loop. It's like Morse code, but not, she says. They all wonder if it could be Donald finally contacting them, but wonder why he would do so now. Olivia decides they need to decode the message to find out for sure. She turns to Walter for help, but he's just kicking back in his examination chair, staring at goodness knows what. "It's gonna be difficult to get any information from him right now," Astrid says, "because he dropped acid." Peter takes a seat beside him. As he calls for Walter, his voice echoes and fades as Carmen's comes to the fore, singing the Habanera. A tiny green fairy materializes in a spray of glitter over Peter's shoulder and then flits off across the lab and past a young blond woman in a lab coat. Carmen fades, to be replaced by an ominous note from the soundtrack. "Walter, are you tripping?" Peter asks. "Most definitely," Walter says.
After a brief interruption by the title sequence, Peter tries again to get Walter's attention. Walter's attention is otherwise occupied, however. "Carla Warren is here," he whispers. "My old, dead lab assistant is here to haunt me," he goes on. "The one that was burned in the fire," he reminds Peter and the viewers at home. Carla gives Walter a look that's both serene and mischievous. Peter decides to press on and tells Walter about the radio. Astrid starts to techo-babble about the signal, but Walter is more interested in the green fairy, who has just landed on his outstretched finger. Walter doesn't have much to say about the signal except that it's in A minor. "What kind of acid did you take?" Peter asks. "Black Blotter," Walter tells him, rather pleased with himself. Then he grows more serious as he explains that he was desperate to remember the plan before "he" takes over. He says Nina's going to help him remove the troublesome pieces of his brain after they've finished the plan. "I don't want to lose you, Peter. I don't want to lose any of you." He turns teary eyes towards the rest of the gang.
Peter tries to reassure Walter, but it's not enough. He confesses that he almost left the tunnels again two nights ago while everybody was asleep. He cries in frustration that he doesn't even know where he was going. "But he does," Carla says. "But he does," Walter echoes because, after all, Carla's just an aspect of his mind. Olivia doesn't quite understand, but Peter knows Walter is talking about the man he used to be. Walter chatters on about his former self like it's a separate entity impelling him to do things. (He multi-tasks by also making himself a little cake with his Easy Bake oven.) It terrifies him that he doesn't know what this other self wants him to do. "I need to figure out this blasted plan to defeat the Observers, and I have to do it quickly, to rid myself of this devil!" He notices that everyone is staring at him and asks, very quietly, to be left alone to do his work.