Plot

Howard receives some shocking news as everyone prepares for the re-opening of the comic book store. Meanwhile, Penny tries to teach Sheldon how to "let it go," but can't follow her own advice when she learns something infuriating about Amy.

When the comic book store reopens, Howard is shocked to find his mothers furniture displayed. Meanwhile, after an incident with Amy, Sheldon is trying to "let it go" with Penny, but she also finds out what Amy has done with her. But just as surprising as what happened with Penny, Howard discovers what happened with his mother...

Sheldon is upset with Amy for helping Barry Kripke with a scientific hypothesis on string theory, which Barry has since posted on-line and has gotten positive reviews. Sheldon's anger is despite the fact that Amy had previously mentioned the exact same thing to him when he was working in the area of string theory, the suggestion which Sheldon ignored at the time. Sheldon goes to Penny for advice on how to deal with his anger. During their discussion on the matter, Penny may come to a better understanding of Sheldon's perspective. Meanwhile, Leonard and Raj run into someone who may or may not be Nathan Fillion. Their possible interaction with him revolves around whether they truly believe him to be the actor or not. And Stuart is about to reopen the comic book store, about which Howard is excited since it means that Stuart will be moving out of Howard's mother's house, subsequently with Howard and his mother being able to resume their relationship the way that it was before Stuart entered her life. Debbie giving Stuart a bunch of her furniture to use in the store opens all of Howard's negative emotions about Stuart and his mother. Those feelings are put aside with some news from Florida.—Huggo

Sheldon and Amy are eating lunch in Amy's lab and Sheldon tells her a science joke. "How many Edison's does it take to screw in a light bulb? None; he stole the idea and doesn't deserve his own joke." Barry Kripke shows up with a thank-you gift for Amy, who helped him with a paper on string theory. Sheldon says that he'd like to read it and to send it to his Bazinga email ID (Bazinga electronic commerce website name was already taken). Sheldon wonders why Amy never offered to help him when he was working on string theory. Amy reminds him that she "did" offer to help him, but he stated that the only math biologists know is "three frog minus one frog equals two frogs."

Howard is on the phone talking to his mother, who is visiting Howard's Aunt Gladys in Florida. He remarks to Bernadette that she is finally in a place where everyone complains about how sweaty they are. Howard is not happy that his mother wants him to check in on Stuart. Howard just wants things to get back to normal between him and his mother.

Sheldon is working on his laundry as Penny enters the laundry room and he explains that he is mad at Amy. Sheldon left string theory because he thought it was a dead end and by working with his rival, Amy may prove that he was wrong. Penny reminds him that he was always for the advancement of science; however, Sheldon is only interested in "his" advancement of science. Penny wants him to "let it go" and to talk to Amy.

Leonard, Raj and Stuart are working in Stuart's new comic book store. Raj tells him that the place looks great and that he should have burnt it down years ago. Howard and Bernadette enter, and they both voice their appreciation for the new store... until Howard sees some of his mother's den furniture in it. This sets Howard off, who says that maybe Stuart should bring over everything else from the den including the clown art he made as a kid. Stuart shoots back that he must have spent ten whole minutes on it. Howard then retorts that maybe he should have gone to art school, opened up a failed comic book store, and mooched off somebody's mother.

Penny and Sheldon are in her apartment as she folds laundry. Sheldon wants to know how to let something go. She advises him to think of something else, and he proceeds to think of a spiny anteater, though it still comes back to Kripke. Penny wants him to try visualization and to imagine his problems are a pen: he should hold the pen and then let it go; however, Sheldon imagines such a special pen that he doesn't want to get rid of it. He tries another approach, telling Penny that Amy has been giving her puzzles to compare Penny's intelligence to that of the monkeys in her lab. Penny denies it until she remembers (via flashbacks) Amy giving her some scissors to assemble, some coins to sort by size, and a banana in a Chinese puzzle box. She gets mad at Amy and Sheldon tells Penny to "let it go", and that he was rooting for Penny. Sheldon wants her to imagine a non-special pen, which gets him thrown out of her apartment.

Howard and Bernadette are sitting on his mother's couch in the comic book store with Bernadette commiserating with Howard. Bernadette reminds him that if the comic book store does well, Stuart will be able to move out of his mother's house. Howard reluctantly agrees, then says he married her so that she could blindly support him no matter how ridiculous he was.

Raj and Leonard are at a deli picking up food for the comic book store party, when Raj spots Nathan Fillion sitting at a table eating his lunch. Raj suggests they ask him to do a guest signing at Stuart's new store. Raj approaches him and the man denies being an actor, then gets insulted when Raj tells him he's not that bad an actor. He again denies being who they think he is and tells them he just wants to eat his lunch.

Amy arrives at Sheldon's apartment just as Penny comes out of hers. Penny, who's still mad at Amy, goes into full-on sarcasm mode, excitedly telling Amy that she got her door open all by herself, and to celebrate, she's going to throw some feces around her cage. Amy gets mad at Sheldon for telling Penny about the tests. Amy then offers Penny $5.00, which is what she paid each of the undergraduate students on which she performed the same intelligence test. Penny just wants her dignity back, so Amy offers her $10.00.

Back at the deli, the man finally admits that he is Nathan Fillion, though a now-skeptical Raj wonders what he is doing eating alone in a deli. Nathan offers to have a picture taken with them, with Raj still skeptical. Nathan then asks if they want a picture of them with a guy that looks like an annoyed Nathan Fillion. That's good enough for Facebook, according to Raj, and the resulting picture shows a smiling Raj, a happy Leonard giving a thumbs-up, and an unsmiling, very annoyed Nathan Fillion.

Leonard and Penny are now on the couch at the comic book store discussing how both Amy and Sheldon did experiments on both of them. Amy and Sheldon walk in and Leonard and Penny say how dare they experiment on their friends and that they don't mind hurting their friends' feelings. Howard comes in, still complaining, and Bernadette wants him to "let it go". Howard excuses himself to take a phone call while Amy asks how she can help make this up to Penny and Leonard. Bernadette tells Stuart that he could've warned Howard about using his mother's furniture, which Raj agreeing when he said it while helping him move it. Howard finishes his call and rejoins the gang, looking like he's in complete shock. his aunt just told him that his mother died after she took a nap and never woke up. Bernadette breaks into tears and hugs him tightly. Instead of being rude, Sheldon sincerely comments, "When I lost my own father, I didn't have any friends to help me through it. You do." These comforting words cause Howard to smile while surprising the others such as Penny who gets broken up and remarks that she thought that he was going to say to "let it go".

Later, the gang is back at Leonard and Sheldon's apartment. Howard is hanging in there, and they're leaving for Florida that night to attend the funeral. The gang reflects on Mrs. Wolowitz's passing. Stuart can't believe she's gone, and will always be grateful to her for taking him in in his time of need, as he would have been homeless otherwise. Raj is going to miss her, and reflects on how she made him feel welcomed when he first came to the United States (especially when she thought that Raj was the gardener the first few years). Penny reflects on how Mrs. Wolowitz had told her that she was too skinny and should eat more. Sheldon didn't like the way that she yelled, but will miss it. Leonard and the rest of the gang then toast Mrs. Wolowitz, saying she was a great mother to all of them (which doubled as a toast by the cast to their own "mother," the late Carol Ann Susi, may she rest in peace.).

Title reference: The reopening of the comic book store by Stuart and a reference to the regeneration process of Doctor Who.