"Portal Enemy" is the forty-fourth episode of Big Hero 6: The Series. It premiered on January 11, 2020 and is the twentieth episode in the second season.
Megan confronts Hiro about being a vigilante and threatens to tell Chief Cruz the truth. Meanwhile, circus acrobat and physicist Sirque steals a secret project from Krei and uses the technology to commit thefts all over the city.
The team is discussing renovations to Frederickson Candy Co. with Roddy Blair where Fred tries to propose ideas of his own, such as a river, on the blueprints. In the city, an acrobatic thief spies on Alistair Krei's limo and follows him across the rooftops. The limo stops at Krei Tech and Krei heads inside to retrieve his opera binoculars; at the same time, the thief discreetly slips in after him. An oblivious Krei enters his office and receives a call from Chief Cruz about the Buddy Guards, while the thief downloads information off Krei's computer and stores it into a hard drive, then slips away, right before Krei notices the download notification on his computer.
At the Cruz residence, Megan Cruz examines Hiro's involvement with Big Hero 6. She heads to Lucky Cat Café and is about to inquire Hiro when Hiro receives a text from Go Go to meet at Krei Tech, and runs off to join his "study group". Hiro, Go Go, and Baymax examine the security footage and see the thief. Hiro has Baymax scan the culprit's eyes for biometric data and identifies her as Celine Simard or Sirque, a former physicist-acrobatic. At home, Hiro analyzes what was on the computer to figure out what Sirque wanted on it when Megan enters inquiring what Hiro is doing. Hiro tries to make another excuse but an irate Megan finally reveals she knows he is part of Big Hero 6.
Hiro begs Megan to keep the secret, but Megan rebukes him for lying to her and feels she must inform her father about their identities, before shooting down that the city needs Big Hero 6 over the police. Hiro convinces Megan to shadow him at headquarters to change her mind, which Megan reluctantly accepts. When they arrive, the rest of the team is shocked and confides in Hiro their doubt; suddenly, they are alerted by a bank robbery. Megan insists on coming, and Hiro takes her on Baymax to the bank where they meet with the rest of the team. They head inside, where Sirque introduces herself and then absconds outside; when the team heads out, Baymax traces her location to Torii Gate Park, which is miles from where they are. Just then, Megan notices mechanical orbs on the ground. Hiro identifies them as offshoots from Project Silent Sparrow, and the orbs function as miniature portal generators. Since the technology is unstable, the portals can cause city-wide destruction if they explode.
To handle the portals, Hiro works on jet thruster modifications. However, he only tests it out once before Fred informs them Sirque is robbing the San Fransokyo Museum of Art. Big Hero 6 and Megan head there where the police confront Sirque with Buddy Guards, but Sirque teleports the Buddy Guards away. Despite the team and Megan's concerns, Hiro goes after Sirque and deactivate the portal to prevent history from repeating itself. Hiro chases Sirque throughout San Fransokyo trying to get her to slow down as the portal's instability begins to corrupt it. Sirque refuses and keeps traveling, and soon, the portal destabilizes. Hiro uses his electro-magnetic lashes to pull the orbs in place. The portal nearly sucks Hiro but Sirque catches Hiro, allowing Hiro to safely stabilize the portal. Sirque thanks Hiro and escapes through the portal, promising to perfect the technology to prevent catastrophe the next time they meet. The rest of the team and Megan find Hiro, elated to see he is alright. As Hiro apologizes to Megan for lying, the police arrive, and before the team takes off, Hiro entrusts Megan with their secret. Cruz then finds Megan, and Megan covers for the team stating Big Hero 6 disappeared. The next day, the team reads Megan's article and find it is about why Big Hero 6's identities should be kept a secret. Meanwhile, Hiro enhances footage of his portal travels with Sirque and sees Baymax's original body floating adrift.
- Sirque (debut)
- Aunt Cass (mentioned)
- Mr. Sparkles (picture)
- Robert Callaghan (picture)
- Professor Granville (picture)
- Tadashi Hamada (picture)
- Noodle Burger Boy (picture)
- Richardson Mole (picture)
- Abigail Callaghan (mentioned, picture)
- Mr. Frederickson (mentioned, picture)
- Bluff Dunder
- General (picture, cameo)
- The title is a play on the term "mortal enemy."
- Sirque's origin place, Lyontreal, is a combination of Lyon—located in France, and Montréal—located in Canada. This makes it the first known hybrid location that does not involve American nor Japanese locations.
- Among the photos that scroll through when Baymax is identifying Sirque are Richardson Mole, Mr. Frederickson, Bluff Dunder, and a handful of SFIT students.
- There are several references to the original film.
- There is archive footage of Alistair Krei and Abigail Callaghan testing out the portal.
- Megan's flight with Hiro and her looking into the skyscraper reflection is a direct homage to Hiro and Baymax's first flight.
- Hiro and his friends mention the first time he traveled into the portal and the loss of Baymax's original body that Tadashi built.
- Go Go's line "Someone has to help" is a reference to Tadashi's last words before he died.
- Krei's computer contains blueprints for Noodle Burger Boy, the neurotransmitter that stuck onto Globby, and Buddy Guards.
- The General from the film makes a cameo in the footage from Silent Sparrow.