Episode Recap
In post-apocalyptic Pasadena, Bert makes his way through burned-out streets to Stuart’s comic book store, where food is bartered for comics and a mysterious portal serves as a rubbish chute. After a regular customer, Kyle, kills another regular during an argument about Hawkeye, Stuart and Bert dispose of Trevor's body through the portal. They are interrupted by another version of Stuart, who has come from a different stream of reality.
The alternate Stuart explains that the devastation around them is not normal and should never have happened. Leonard, Sheldon and Howard built a quantum device that malfunctioned and altered reality, creating the violence, destruction and dimensional rifts that Stuart and Bert now regard as normal. The device is still at Caltech and could be used to put everything right, but the traveler begins slipping through a wormhole before he can deliver the full instructions. He disappears after telling Stuart to find the machine and an unidentified man who can help him fix it. Bert is confident he got the gist of the message.
Outside the store, Bert argues that the appearance of the alternate Stuart has given them a quest and a chance to repair the world. Stuart questions whether their reality is really so bad, but when another zombie hand emerges from the ground, Bert stamps it down and declares that there is room for improvement. The two set off for Caltech.
Using a Thomas Guide because civilization’s collapse has rendered Stuart’s phone useless, Stuart and Bert cross Pasadena. They pass Penn and Teller performing for food before reaching a crowded market outside the ruined Rose Bowl. After Stuart stops to barter for dental floss, a rifle-carrying robber confronts them and reveals herself to be Denise. She and Stuart had each believed the other was dead. Denise has since become involved with Gary, whose former girlfriend was eaten by cannibals. Stuart explains that an alternate version of himself has sent him on a journey to Caltech to undo the apocalypse. As Stuart and Bert continue their mission, Gary predicts that they are going to die and Denise agrees.
Stuart and Bert reach the heavily fortified perimeter of what was once Caltech. Denise and Gary catch up with them, having decided to help. Gary, a former Army Special Forces soldier, proposes drawing the guards’ attention at the main gate while the others enter beneath a supply truck. He runs out to create the diversion and is immediately shot dead. Armed guards surround Stuart, Bert and Denise and take them prisoner.
Inside Caltech, the three are locked in Bert’s former geology lab, where they discover a dishevelled Raj. Years of captivity have left him paranoid and cynical, but he has used the time to figure out what happened to reality. He explains that Leonard, Sheldon and Howard’s vari-state quantum interference device malfunctioned and changed the universe, history and reality itself. Raj believes he could reset the universe if he reached the machine, but it is guarded around the clock by forces loyal to the "Evil One" who rules Caltech. Stuart declares that his alternate self said he was "the chosen one" who can set things right, although Bert quibbles with that interpretation.
The Evil One is revealed to be Barry Kripke, now the Grand Caliph of South Pasadena. Kripke explains that he seized power after civilization collapsed and now controls the food, weapons and women at Caltech. Happy with his position and authority, he has no interest in restoring the former reality. When Kripke turns his attention to Denise, Stuart claims that she is with him in an attempt to protect her. Kripke orders his guards to wash Denise and take her to his room, but when she says she would rather die, he tells them to wash and kill her instead. Stuart is knocked unconscious when he protests.
When Stuart regains consciousness, he is determined to rescue Denise. Bert realizes that the contents of his old geology lab could help them escape. Raj is unimpressed at the idea of throwing rocks at the armed guards and is unmoved when Bert demonstrates the explosive reaction between potassium and water. When Bert clarifies that he intends to make grenades, Raj wonders why he never thought of that.
Later, a guard enters the lab intending to execute the trio, but Bert kills him with one of the grenades. Stuart, Bert and Raj fight their way through Caltech, using the explosives against Kripke’s guards as they search for Denise and the device.
Meanwhile, Denise is tied to a chair in another room as she talks to her guard about his job in the "before times." Kripke visits her and admits that ruling his post-apocalyptic fiefdom is lonely because the women in his harem care only about the food, medicine and free childcare he provides. Denise says she has changed her mind about having dinner with him and persuades him to untie her, only to attack him and escape.
Denise reunites with Stuart, Bert and Raj as they descend a staircase at Caltech. After another grenade kills the guards outside the lab holding the machine and blows open its door, the group finally reaches the vari-state quantum interference device.
As Raj works to reconfigure the machine, Stuart assumes that restoring reality will also restore his relationship with Denise, but she warns him not to rush her while she is still grieving Gary. Before Raj can finish, Kripke arrives and shoots him, determined to preserve the world in which he holds power. Bert attacks Kripke while Stuart tries to help Raj, but Raj dies before he can explain how to complete the reset.
Using Raj’s notes, Denise guides Stuart through the remaining instructions. After Stuart completes each step, Denise notices that the notes continue with “But first…”. As the device begins to glow, Denise ducks behind a table while Bert overpowers Kripke beside the machine. The device opens a wormhole and pulls in Stuart, Bert and Kripke, leaving Denise behind in the apocalyptic reality.
Stuart, Bert, Kripke and the device emerge from the wormhole inside the comic book store in an apparently peaceful Pasadena. The zombies and giant moths are gone, Stuart’s injuries have healed and ordinary life has returned outside. Although Stuart is concerned that Denise did not come with them, Bert assures him they will find her and that everything is back to normal. The closing shot reveals identical round electronic devices implanted in the backs of their necks, each showing a green light.
