Doctor Who Season Finale Explores Ruby Sunday’s Mysterious Lineage

The following contains spoilers from the Doctor Who season finale, now streaming on Disney+.

The Disney+ sci-fi series has advanced to its season finale, placing the Doctor and friends against none other than Sutekh, the God of Death. In this climactic episode, we discover that Sutekh’s mission is to solve the mystery of Ruby Sunday’s lineage. After all, he was present on Christmas Eve 2004, tethered to the TARDIS, unable as anyone else to see under the hood of Ruby’s mother.

The Doctor discerns that Roger ap Gwilliam, a future politician from the episode “73 Yards,” might hold the key, given his implementation of enforced DNA registration. The Doctor, Ruby, and Mel travel to the 2040s to match Ruby’s DNA to someone in that governmental database. When a result appears on the monitor, Ruby tantalizes Sutekh with her mother’s identity, stepping closer before dramatically shattering the monitor on the floor.

Using this ruse to approach Sutekh, Ruby had used the ruse to get close enough to attach a leash to Sutekh’s beastly form. The Doctor attaches the other end to the TARDIS; Fifteen then drags Sutekh through a turbulent journey across space. By figuratively bring[ing] Death to death everywhere!, he resurrects everyone who had turned to dust earlier in the episode.

After depositing Sutekh in a void, everyone reconvenes at UNIT headquarters, where tech helps them draw Ruby’s DNA match from the 2040s database.

It turns out that Ruby’s mother is Louise Allison Miller, a 35-year-old nurse in Coventry who had given birth to Ruby at age 15. Troubles with Louise’s stepfather forced her decision to place Ruby somewhere safer—a choice that perplexed many, including Sutekh himself. The Doctor realizes She was important because we think she’s important… Her sheer existence was more powerful than Time Lords and gods.

This understanding leads everyone at UNIT to connect that back in 2004 when Ruby’s mother pointed out a street lamp bearing the name Ruby Road—it wasn’t an accident. Ruby realizes her own mother chose her name purposefully.

After briefly uniting with Louise and developing bonds with both her and Carla, Ruby prepares for more adventures on the TARDIS. Upon learning that her father has also been located, it’s clear that her tenure as a companion concludes.

The Doctor reassures Ruby: Don’t be sorry at all… I’ve shown you monsters and planets and legends…. As she readies for her own journey, Ruby wonders if she will ever cross paths with the Doctor again. The enigmatic response: I will see again, because you changed me…

Before fading out, the finale hints at a disturbing future without Ruby for the Doctor.

What a very happy ending for little Ruby Sunday…, observes Mrs. Flood from a rooftop scene with her white parasol. The striking visuals add depth and poignancy. Flood ominously reveals: I’m sorry to say his story ends in absolute terror…, closing with a haunting farewell: “Night-night!”