Episode 7 of Doctor Who unveils the grand finale in a two-part spectacle, commencing with Kate Lethbridge-Stewart's anticipation for the TARDIS' return to UNIT headquarters. As the vessel spins gracefully within, Rose emerges to greet her, accompanied by Morris Gibbons, UNIT's new scientific advisor, a precocious genius at just 13 years old. Harriet, who will later emerge as a pivotal character, also joins the ensemble.
After these introductions, our focus shifts back to Susan Twist, a figure who, as we're reminded, traverses every time-zone. For those who may have missed the visual cues throughout the season, the Doctor describes her appearance in detail. It transpires that Susan Twist is actually an IT prodigy named Susan Triad, poised to unleash her software globally, free of cost. A generous offering from S Triad Technology, where "S Triad" is a clever anagram for TARDIS. Given that Susan is the moniker of the First Doctor's granddaughter, the connections seem unmistakable.
If this is indeed the legendary Susan, the Doctor believes she may hold the crucial clue they've been seeking. Mel, undercover on the media team, also finds herself amidst this puzzle. Surprisingly, Susan Triad appears to be a genuinely kind soul. But there's another enigmatic figure they must unravel—Ruby Sunday.
The Doctor steadfastly refuses to traverse his own history, having seemingly time-locked himself out of Christmas Eve 2004. He struggles to decipher the meaning of the snow, but Harriet suggests utilizing CCTV technology from that era, combined with UNIT's advanced equipment, to "enhance this grainy image" and determine Ruby's mother's identity.
Meanwhile, at Ruby's abode, she retrieves a tape and invites Mrs. Frost, the neighbor who broke the fourth wall at the season's onset. Once everyone departs, leaving Mrs. Frost to oversee Mrs. Sunday, her demeanor undergoes a sudden transformation. She claims that a storm is brewing and "he waits no more." This abrupt change in character strikes a chord, reminiscent of a scene from Happy Gilmore, involving a retirement home.
As the ominous storm clouds gathered ominously over London's skyline, Kate imparted some profound words of encouragement to the Doctor, affirming that wherever he ventured, he brought joy, not despair. Their embrace was briefly interrupted by Mel's arrival, who informed them that Susan was about to deliver a momentous speech at 3 pm. A DNA analysis confirmed Susan's humanity, yet Kate speculated that she might be a chrysalis, destined to transform into something unknown even to herself.
As the team gathered at Unit with the tape, Colonel Winston, the head of Time Window Security, ushered them into a unique chamber within the Unit HQ. This chamber harnessed the collective nuclear might of Europe, projecting an image from the past. Their objective was to utilize this Time Window to reconstruct the events of Christmas Eve 2004 and unravel the mystery surrounding Ruby Sunday.
Ruby's mother, a woman without a profession, inquired about the cost of this endeavor. As the tape was analyzed, Ruby and the Doctor were transported back to that fateful Christmas Eve. The Time Window was robust, and memory, it seemed, was the ultimate gift of time, allowing them to witness the past with clarity and sound.
Ruby remained unable to glimpse her birth mother, concealed beneath a hood, but she could hear her weeping. The Doctor conjectured that time was fluid, constantly evolving, and he noted the birth mother's fleeting gesture of pointing towards him before she vanished from sight.
As the memory dissipated, a transformation occurred. The Tardis and Colonel Winston vanished, replaced by a swirling mass of fiery shadows that materialized before the Doctor. This, it seemed, was the Beast, although it was a familiar sight from the Tennant era, revealing that this was not the true threat. The Colonel somehow managed to communicate with them, revealing that whatever lay beyond the shadows had been awaiting their arrival for an eternity.
The vision abruptly terminates with a deafening explosion, and the Colonel materializes as a stone figure, lying lifeless on the ground. Kate observes, struck, that he seems to have been entombed for a century. As the Colonel lies inert and the countdown to Triad's activation nears its conclusion, Mel escorts the Doctor to Susan's side. The Doctor discovers that Susan hardly sleeps, her nights punctuated by nightmarish visions of the Doctor's far-flung adventures. Shaken, Susan prepares to deliver her speech, while Unit's investigators uncover a sinister presence at the heart of the mysterious shape.
Looming ominously, the TARDIS appears once again, shrouded by a strange entity mere twenty meters to the north. It seems the TARDIS has become a trap... but will the Doctor brave the danger and lend his aid? Will he confront the threat head-on? After his recent abandonment of Ruby in pursuit of fleeting pleasures, it is unsurprising that he elects to remain, keeping a watchful eye on Susan.
Susan strides onto the stage, her speech punctuated by a spirited dance, a subtle mockery of former Prime Minister Theresa May. She decries the tech billionaires, their avarice and the mayhem their technology has wrought. Susan declares that today marks a turning point... but then she deviates from her script. Her eyes glaze over, her body taken over by an unseen force.
As the Unit evacuates, they scan the TARDIS, revealing a lifeform encircling it. Kate begs the Doctor to intervene, but he refuses, insisting that Ruby should be sent through the Time Window instead. Harriet's possession soon becomes apparent, her surname Arbinger revealing her true identity as Harbinger. As the Time Window recedes, reverting to Christmas Eve 2004, Susan appears to be consumed by an unknown force. It dawns on them that the anagram they had deciphered was incorrect.
It is not Susan, but Sutekh, the God of Death, who has emerged. Sutekh is no stranger to the Doctor's universe, having made his mark in the show's illustrious past. As the TARDIS is ensnared by a mysterious canine creature, Sutekh's malevolent influence spreads. The Doctor stands frozen, his courage shattered by fear.
