Representing the Frederickson family in his father's place, Fred invites Hiro, Baymax, and Go Go to the unavailing of a new product at Krei Tech Industries called "Buddy-Guard": A small military grade drone designed to be a personal bodyguard. It is capable of countering any attack, armed with lasers, bolas launchers, and flexible display technology that can turn it invisible. The flexible display technology was designed by Doctor Mel Myers, who is not pleased with what Krei has done with his invention. He originally wanted it to be used for fun things at surprise parties. When Krei refuses to give back Mel's plans, he vows to get back at him. Meanwhile, Hiro struggles with keeping his Big Hero 6 identity a secret from his Aunt Cass, who almost busts him from time to time. He cannot just tell her he is a superhero because she would go berserk. So, he decides to find her a date to distract her. Later at San Fransokyo Tech, Hiro and his friends are visited by Krei, who wants them to inspect the Buddy-Guard. Taking up what Hiro and Go Go said earlier about safe guards, it turns out the drone has some glitches that his employees could not decipher. He personally wants Hiro and his friends to make sure the drone is safe in exchange of keeping their Big Hero 6 identities a secret, much to their shock. As Krei leaves, he bumps into Cass, who was delivering Hiro's chemistry homework. Much to Hiro's displeasure, Krei and Cass instantly develop a mutual attraction for one another. He tries to get his aunt away from Krei, but it is no use. Krei asks her out for dinner and she accepts.
By evening, Hiro is still unhappy with his aunt dating Krei. While it was his idea to get Cass to date, he did not want it to be with Krei. Krei then shows up at the Lucky Cat Café with a bouquet of flowers. Cass also shows up, dressed and ready to go. Krei presents the flowers to her, and she gives them to a sulking Hiro before leaving. After dumping the flowers in the toilet, Hiro worries about what might happen if Cass and Krei's date goes well. Afraid they might get married, Hiro decides to follow them and make sure their date does not go well. Meanwhile, Honey, Go Go, and Wasabi are still at work on the drone. Fred later shows up with some dinner for everyone: Noodle burgers and coke. Fred accidentally spills coke on the drone, which causes it to power up and attack them. They eventually disable it and realise that its threat assessment program was shorted out when it got soaked, making it think they were all enemies.
Hiro and Baymax follow Krei and Cass to a fancy restaurant, and Hiro sneaks in through the backdoor. He finds Cass and Krei sitting at a table, getting more and more acquainted with one another. They both realise that they love origami. Hiding under a serving trolley, Hiro causes a waiter to trip and spill Krei's food on his shirt. He gets ticked off, but then tries to be calm and forgivable in front of Cass. Then he goes to the washroom to get cleaned up, where he is ambushed by Doctor Mel. He has him tied up, and then walks out of the washroom looking like Krei, wearing his flexible display invention around his face. He prepares to go back to Krei Tech to steal back his plans, but is forced to take Cass along when she thinks he is the real Krei. Both Hiro and Baymax notice something is off, which is confirmed when Hiro finds Krei tied up in the washroom.
Upon arriving at Krei Tech, Mel breaks into Krei's office, but Krei and Big Hero 6 are already there waiting for him. After taking back the the flexible display plans from Mel, Big Hero 6 tell Krei that he cannot sell those drones because of what happens when they get wet. Krei agrees to delay shippings until they are perfected. He then tries to get the drones to apprehend Myers, who gets behind Fred. He ends up tickling him, causing him to ignite his flamethrower, setting off the sprinklers. The drones get wet, and they go haywire like before. They easily beat Big Hero 6, and then chase after Mel. Cass is still in the limousine showing pictures of Mochi to the chauffeur. Mel shows up and gets in the back, while Cass takes the wheel when the (totally not interested) chauffeur runs off. Racing through the streets, the drones chase after Cass and Mel. Hiro and Baymax eventually catch up with them after breaking free of their restrains. Baymax destroys two of the drones, and Hiro hitches a ride on one until it crashes. Cass and Mel escape to the woods, but one remaining drone catches up with them. Cass and Mel try to escape on foot, but become cornered until Baymax's rocket fist takes out the last drone. Afterwards, Mel is arrested, Cass dumps Krei after seeing his true colors, and Hiro has decided to never again meddle in his aunt's personal life.
- Ryan Potter as Hiro Hamada
- Scott Adsit as Baymax
- Génesis Rodríguez as Honey Lemon
- Khary Payton as Wasabi, Ninjas, Rich People
- Jamie Chung as Go Go Tomago, People in Line
- Brooks Wheelan as Fred
- Alan Tudyk as Alistair Krei, Krei-Scientist, Rich People
- Maya Rudolph as Aunt Cass
- Sean Giambrone as Richardson Mole
- Laura Silverman as Judy, People in Line, Rich People
- John Ross Bowie as Dr. Mel Meyers
- Jeff Bennett as Chef, Rich People, Security Guard, Waiter
- It is revealed in this episode that Krei knows the identities of Big Hero 6.
- Felony Carl's age is revealed to be forty-two.