Although it's been a long wait for the rest of us -- six months have passed since the Series 5 finale -- the Doctor Who Christmas special, "A Christmas Carol," opens with Amy Pond and Rory Williams still on their honeymoon, aboard a space liner careening toward a cloud-covered world. As the crew attempt to stabilize the ship, Amy, once again in her kiss-o-gram police costume, calls for the Doctor.
Planetside, we learn the clouds are the domain of the bitter Kazran Sardick (Harry Potter's Michael Gambon), son of the heartless man who created the spire that controls them.When the planet's president alerts him to the trouble in the skies above, Karzan declares he has no problem letting all 4,003 passengers die. He also ignores the pleas of a destitute family that begs for the release of a long-frozen relative, Abigail (Welsh singer Katherine Jenkins), so she may spend Christmas with them. Karzan refuses just as the Doctor arrives in a burst of flame and bellow of smoke through the fireplace. "Sorry, Christmas Eve on a rooftop, saw a chimney, my whole brain just went, 'What the hell'!" the Doctor explains to the astonished group.
Once he's surveyed his surroundings, the Doctor finds the controls for the clouds. Unfortunately, it is an isomorphic system, which means only Kazran can allow the ship to land. After the Doctor's own plea falls on deaf ears, Abigail's nephew hits Kazran with a rock. As the old man goes to slap him, he pauses and reconsiders striking the boy. The Doctor takes note of it. After the family is escorted out, the two have a brief conversation in which the Doctor lets Kazran know he's "halfway out of the dark." Despite getting under the old miser's skin a bit with an understanding of how much he is not like his father, the Doctor's second attempt to secure a safe landing for the ship also fails.
Outside the spire, Abigail's brother-in-law tells him Kazran allows a few of the fish that swim in the sky to fall closer to the ground. On the planet, the fish stay in the always-foggy air instead of the sea. This further cements the Doctor's belief that Kazran can be swayed. While talking to Amy on a long-range communicator, a Christmas carol blurts out on a nearby speaker. It gives the Doctor an idea.
"Tonight, I'm the ghost of Christmas past," he announces to Kazran upon returning to the spire. The old man is watching home movies from his childhood, and the Doctor inserts deleted footage of Kazran's father Elliot (also played by Gambon) hitting him because the boy wanted to let a fish into his room. After another war of words, the Doctor slips into the past and appears on the movies talking to both the younger and older Kazran. He resolves to lure a fish into the boy's room.
Setting up the sonic screwdriver as bait, the Doctor and young Kazran hide in a closet and wait for something to come through the open window. A small fish swims in and plays with the emitter bulb. The Doctor tells the boy to wait in the closet while he inspects the fish. Soon after, a shark swims into the window, eating both the fish and the Doctor' trusty tool. Retreating into the closet, the Doctor is pursued by the shark as it bursts through the door, its mouth wedged open. Figuring this is the screwdriver's doing, the Doctor reaches in and retrieves half of the device before determining the shark is dying from the trauma of the whole affair, and can't make it back to the sky without the help of a life-support system. Young Kazran suggests the cryogenic freezers where his father keeps the "surplus population" that owes him money.
Once inside the freezer chamber, the Doctor recognizes Abigail from before. He releases her just as the shark swims in, attracted by the other half of the screwdriver. Abigail begins to sing, calming the shark long enough for the Doctor to put it in her freezer. All three enter the TARDIS, and old Kazran, his memories rewriting themselves, recalls the wonder at it being bigger on the inside. The Doctor opens the doors and they all see that they are up in the storms. The shark is released, safe again among the other fish that roam the skies. The group return Abigail to her sleep, but young Kazran promises he and the Doctor will visit her every Christmas Eve, much to the Doctor's surprise.
The next year (though an instant for Abigail and seconds for the Doctor), the Doctor devises a way for the trio to attach a sleigh to the shark. Riding around the town, they confuse at least one young girl expecting it to be Father Christmas. The next couple of years flood into Kazran's memory as the Doctor takes them to Christmas Eves on Earth all through history. In his study, the old man looks at photos of the group in Egypt, Paris, and other exotic and time-lost places. With each passing visit, Kazran dresses more and more like the Doctor -- even appearing one year in a long scarf. At the end of every Christmas Eve, Abigail thanks the Doctor until, one year, she notices Kazran has grown to be a man. She requests to take a look in on her own family.
When they arrive at her family's home, she peers through the window and tells Kazran they "live the life I can never lead." The Doctor then appears in the window and ushers them into the home, where Abigail tells her sister about the group's Christmas Eves. Her sister is astonished to find the young Kazran so nice and warns Abigail that he could still turn into the despicable man his father is. Abigail is now too smitten with the young man to pay it much mind. As she insists that she cannot stay for Christmas dinner, the whole family, Kazran, and the Doctor have dinner right then.
As they return to the freezers, Abigail asks the Doctor for a moment to say goodnight to Kazran in private. He steps away and the young man chases after him. "She's going to kiss me, isn't she?" he asks. The Doctor, still uncomfortable about such things, ushers him back to her. They kiss and back into the freezer she goes.
A few more years pass and the Doctor takes them to a Christmas party in Hollywood. We know this because the Doctor's apparently agreed to marry Marilyn Monroe. One wonders if this is how it went down when he married Queen Elizabeth I. At this same party, Abigail tells Kazran her great secret: She volunteered to go into the freezer because she was dying and now, after all these Christmas Eves together, she only has one more day to live. When the group returns to the freezers, Kazran tells the Doctor not to return next year, but neglects to explain why. "Christmas is for children," he says. Saddened, the Doctor leaves the broken screwdriver with Kazran and tells him to use it if he ever wants him to come back.
Old Kazran has a memory of just such a moment: His father has completed the control system and explains how it works. As the younger version of himself rushes back to his room to reach for the screwdriver, he sees the Doctor peering in through the window. Instead of activating the device, he closes the blinds. Back in the present, the old miser finds the broken screwdriver in a drawer. Though he had all of these experiences, he is still a deeply embittered man.
Just then, Amy appears via hologram, claiming to be the ghost of Christmas Present. She leads Kazran into the freezer room where holograms of the ship's passengers sing Christmas carols. Though this attempt to warn Kazran's heart also fails, Amy learns the real reason he sent the Doctor away. "What day would you choose?" he asks her.
The Doctor arrives as "Christmas Future," but Kazran, now aware of the plan, says he knows how he will die, and he doesn't care about the people on the ship. "I'm not like you," shouts the old man. "I don't and never will care!" After the outburst, the Doctor motions toward the TARDIS. Kazran looks to see himself as a boy step out. "What do you think?" asks the Doctor. The boy looks at his old self and asks "Dad?" With that, the old man rushes to slap the boy, but stops and hugs his younger version instead, proving the same matter can exist in the same space without destroying itself when near the TARDIS.
Now changed, Old Kazran is ready to help the Doctor. All three rush to the control system, but Kazran's change of heart has altered his bio-signature too much; the unit will no longer respond to him. When presented with the screwdriver, the Doctor devises a way to stabilize the clouds … but it involves a sacrifice on Kazran's part.
As Kazran awakens Abigail, she tells him they've had many Christmas Eves together and "It's time for Christmas Day." With the two halves of the screwdriver still signaling to one another, the Doctor sends Abigail's voice into the storm, allowing the ship to land and, as a side-effect, snow falls all about the city. It is a Doctor Who Christmas special after all, snow has to come by some absurd means. The old Kazran watches the TARDIS dematerialize with his younger self inside. Once it is gone, the sleigh is left in its spot.
Interesting side-note: Abigail's song makes reference to silence. "The Silence" will be a major enemy in the upcoming season.
Amy and Rory find the Doctor making small snowmen. She asks if there is any way he can help Abigail, but there is nothing he can do. "Everything's got to end sometime, otherwise nothing would ever get started," he tells her. As the police box dematerializes, the camera pans up and we see Kazran and Abigail taking one last ride together in the shark-pulled sleigh.