The episode begins in 1994, when Robin's dad took her to Central Park for the first time. He didn't like New York much, saying it was like Edmonton without all the culture. Robin walked off on her own, dreamed of moving to the big city one day to marry a sophisticated man, and buried a locket in the park that would be her "something old" at the wedding. Back in the present in Central Park, and Robin is telling her father about that moment. He gets a call from Barney, who he is calling to meet for laser tag in 15 minutes. Her dad takes off instead of helping her dig up her "something old" at the park.
Meanwhile, Marshall and Lily are packing for their year-long stay in Italy. They're going to have to throw some things away. Marshall wants to save his binders full of evidence of Sasquatch's existence, but wants Lily to throw away their handbags. They decide to call in Ted to help them make their difficult packing decisions. Its decides that Ted will tell them what goes to Italy and what goes in "the triangle," the mystical spot on the sidewalk in front of the apartment building where things are placed and quickly disappear. The main rule is whether something has been used in the past year. Quickly enough, Marshall's jump rope is gone. Lily tries to bribe Ted with some cash to let her keep a handbag, but he's not letting it happen. Still, he keeps the cash.
Barney and Robin's dad are having some father-son bonding at laser tag. Some of Ted's packing decisions seem a little arbitrary to the untrained eye, as he dumps a tour book about Italy into the triangle box and puts an actual musical triangle into the Italy box. Ted rules that a leaky old bean bag chair covered in bong water and Cool Ranch Dorito crumbs can go to Italy, but it's becoming clear to Marshall and Lily that he's ruling to keep the things he likes, including an old karaoke machine they used to sing in the New Year in 1992. Barney and Robin's dad start to argue about who's the "point guy" in laser tag and begin to get into it about the Scherbatsky stubbornness.
Robin's dad tells Barney he'd better get used to it if he's marrying Robin, but Barney says Robin isn't near as stubborn or crazy as her father. Robin is frightening children and parents with her mad digging around Central Park. The argument at the apartment continues over the bean bag. Ted finally convinces Marshall and Lily to take it to Italy. They send him off to get them a couple of hands-free belt satchels. Barney and Robin's dad are assembling their teams of kids at laser tag to go against each other in an epic battle. Ted is coming back from getting the fanny packs and realizes he's been set up. He runs back to the apartment and catches Marshall and Lily putting the bean bag into the triangle on the sidewalk. He says he'll stay there all day, even if it means canceling a meeting about designing a new building.
Robin calls Barney and asks for help with her issue, but she tells him it isn't urgent and lets him get back to laser tag. Ted goes on to explain he's so wrapped up in the bean bag because it was the first piece of furniture they bought when they moved to New York. He says he knows he's being crazy, and asks them for a moment with the chair, to say goodbye. Ted stands up to hail a cab and before he's even in the car the bean bag has disappeared from the triangle. Robin calls Ted to ask him for some help with her issue, not fully explaining what it is. He is on his way to his meeting and she tells him her thing is stupid, and lets him go. It's getting down to crunch time and the kids on Robin's dad's laser tag team revolt because Barney's team seems more fun.
Robin is still digging, exasperated, when she tearfully looks up and sees Ted strolling her way. Ted says he's there to help because she said "'nah, it's stupid," which everyone knows is Robinese for it's important. She says not everyone knows, referring to Barney having not responded. She asks him about his important meeting and he says, "Nah, it's stupid." Ted tells her that if she told Barney she needed him he'd be there in a heartbeat. She says she didn't have to tell Ted, but he's there. Barney and Robin's dad are in their final confrontation at laser tag. Robin's dad is face to face with Barney and goes to shoot, but his gun won't work. Barney holds up two batteries and asks if these are what he is looking for.
While he helps her dig, Robin explains the story behind the locket. Ted thinks it's funny that Robin ever imagined herself with a "something old" at her wedding and mocks her for being "a girl". She finds the locket. She's relieved and Ted asks what's really going on with the locket. She then admits that she's nervous about marrying Barney. She says that in many ways he's growing into a mature adult. Just then, we see a quick cut of him laughing maniacally as he tells her dad he's going to shoot him with his own gun. Robin goes on to say she still doesn't know if he's ready for this, nor if she is ready for it. She thinks that if she could find the locket it'd be a sign that everything was going to be ok. She opens the box and it's empty.
Back at the laser tag battle, Barney asks Robin's dad if he has any last words. He tells Barney that seeing in battle that Barney is ruthless, manipulative and untrustworthy, has convinced him Barney has all the qualities he had wanted in a son. Barney drops the gun and they decide to leave. But first, they shoot all the kids. Robin is bummed and Ted gets a text. It's a picture from Marshall and Lily. They took the bean bag and they're holding up a sign that reads "Italy" over it. He smiles, looks at Robin, and texts back, saying he loves them but they should get rid of the horrible chair.
Back at the apartment, Marshall reads the text and is relieved. Ted tries to convince Robin the missing locket isn’t a sign from the universe. While he is at it, a thunderstorm starts and rain pours down on them. Robin, still crying, reaches out and holds Ted's hand. The episode ends at this point.