Warning: Spoilers for ‘Doctor Who: Flux Chapter Five‘ incoming.
Doctor Who fans are losing it on social media as a beloved character long since seen on screen made a grand return in the show’s latest episode. Season 13, a multi-part epic subtitled Flux, reached its penultimate installment this Sunday. Called “Chapter Five: Survivors of the Flux”, it added another thread to the interconnected, complex plot that reintroduced alien-busting organization U.N.I.T. — along with its head, Kate Stewart (Jemma Redgrave).
This is a big deal as U.N.I.T. was previously revealed to have been shut down in a throwaway line back in 2019. Since then, fans have wondered what happened to the stalwart institution which has been part of Who lore since the ’60s.
In this episode, we finally discovered the truth. Time-traveling villain the Grand Serpent was revealed to have been manipulating U.N.I.T. behind the scenes for decades, getting himself to a place of power where he could close it down in 2017, setting up his allies the Sontarans to invade Earth unimpeded.
The only person standing in the Serpent’s way was Kate, daughter of classic Who character Brigadier Lethbridge-Stewart. In an epic scene showing her intelligence and strength, Kate stood up to the evil alien and proved to him that she wouldn’t be pushed around.
And fans are going crazy for it on Twitter.
After standing up to the villain, fans feared for Kate’s safety — especially after the Serpent blew up her house. Thankfully, Kate revealed to her colleague Osgood (another fan-favorite, though sadly they didn’t appear) that she was “going dark,” explaining why she’s not been seen in the Jodie Whittaker era.
The next-time teaser promised that Kate will come back for the season finale, so fingers crossed she’ll share some scenes with the Thirteenth Doctor. That will bring Kate up to five Doctors she’s starred opposite, following David Tennant, Matt Smith, Peter Capaldi and John Hurt.
Doctor Who: Flux airs on BBC America.