Donna is coming down the aisle in her wedding dress. Family surround her. It is the happiest day of her life. Suddenly she starts glowing and disappears as a sparkling beam of light through the ceiling of the church to materialise, many hundreds of light years away, inside the Doctor's Tardis. We can only assume that she went via the Time Vortex. Huon or hunon or hunan, (couldn't really understand what was being said. I'll wait to read the script) anyway, these Huron particles or whatever are what attracted an excited Donna to the Tardis control room. But we find that out later.

In the meantime, Donna must get back to the wedding. After insults are exchanged and the Doctor gets a bit teary over Rose again, they land in England and try to get a taxi to get her to her wedding. When they finally succeed they realise they don't have any money. The Doctor goes and queues at an ATM while Donna tries to find a taxi that'll take her.

Donna gets into a taxi just as the Doctor is confronted by 3 santas with deadly trumpets. He'd previously got money out of the ATM with his sonic screwdriver and used it this time to set the ATM on EJECT, blasting cash in front of the Santas just as Donna pulls away in a taxi driven by a pilot fish santa.

The Doctor rushes back to the TARDIS and with some string and a hammer manages to get the TARDIS' flight systems running.

Donna realises that the taxi is not stopping where it is supposed to and pulls off the santa mask to reveal an alien robot driving the car. She starts to freak out and finds that the doors and windows are locked. As she starts screaming for help she suddenly sees a blue police box materialise on the motorway a few cars behind her. With a few spins in amongst the vehicles the TARDIS comes alongside the Taxi and the Doctor appears, unlocking the windows and doors of the taxi, immobilising the robot and asking her to jump. 

She does and they land on the top of a nearby building while the TARDIS repairs itself from the damage caused by the flight.

A bit of a discussion and the Doctor gives her a biological signature dampening ring (biodamp ring) to prevent the santas from finding her. They head to the location of the reception and find that the wedding guests had the reception without her. Donna is very upset that they were partying and makes sure she gets all their sympathy for her ordeal.

The Doctor borrows a mobile and searches the net to find that H C Clements, the company that she works for, used to be the company that supplied intricate security devices to sole proprieter Torchwood.

He also looks at the video tape of her disappearing and realises that she was taken by Huon particles. He then realises that the biodamp ring won't protect her because Huon energy is over 4 billion years old. Then he realises that they've already been tracked and are surrounded by deadly santas. Then he realises that the santas are carrying remote control devices. Then he realises that the reception centre has Christmas trees and that they may be dangerous.

Then he realises that... just kidding. But the action continued much the same throughout the story. The Doctor continually realising something new, which sent Donna up the wall.

The balls on the Christmas trees start to float in the air then plummet down as mini grenades, exploding throughout the reception hall. The santas come in just as the Doctor makes it to the sound system with his sonic screwdriver and blasts the robots to bits using sound waves.

Investigating the robots he realises that they're being controlled by someone else, they're not scavengers anymore.

Up in a Bethlehem-Star-shaped Arachnoid ship, a giant humanoid spider cackles gleefully to herself and with one spindly leg points at the Doctor through her scanning equipment.

She materialises in a room where a tunnel has been built to rescue more of her kind trapped beneath the Earth.

The Doctor, Donna and her fiance head to HC Clements to investigate the company. After an amusing ride on some Segway vehicles they find a laboratory where the Doctor discovers the Heuon particles are distilled from the Thames. Lance disappears as a wall is raised to reveal the the Empress of Racnoss. Hmm, the TARDIS telepathic circuits must have had fun translating that planet name. Arachnoids, Racnoss, arachnophobia?

Anyway, they find out that Lance has been helping the Empress and that he'd been deliberately poisoning Donna with a cup of coffee every morning containing Huron particles. The Hewron energy becomes active only when it becomes part of a human being. And as the ship the Racnossians had used to escape a war with the Time Lords could not be reanimated without the key of active hunon particles, a suitable human had to be found.

The Doctor uses the particles to draw the TARDIS to them and they head back 4.6 billion years to see the birth of the Earth. They find that the Racnossoids ship was the first piece that started bringing the Earth together in that original dustball.

The Empress decides to use Lance instead and has found a way to mix the fluid so that, instead of having to slowly dose someone over 6 months with Donna, she can have Lance as an effective key within minutes.

The Empress activates him and drags the TARDIS back to the present via the Time Vortex. Must have been why the Time Lords wanted the Racnosaurs wiped out, the energy is very powerful.

The Doctor manages to materialise the TARDIS a little bit away from the laboratory and heads off to try and stop the Empress from awakening her children.

She captures Donna again then feeds Lance to the other Racnoss members. She's built a bloody great big shaft all the way to the centre of the Earth to the ship and the Doctor knows that if those Racnossans awaken, they'll eat everything on the Earth. So he blows a hole in the wall with the Christmas tree balls and a remote control that handily fit in his bigger on the inside pockets, and lets in the Thames, draining the river into the hole and crushing the aliens under the sheer weight of water.

(Hmm, I wonder if the Daleks found this hole in the 22nd century when they invaded?)

The Empress escaped, of course, but she arrived in her ship just as UNIT blew it up. The Earth is saved.

The Doctor is invited to Christmas dinner with Donna but he declines, causes it to snow and disappears with a lump in his throat about Rose.

I enjoyed this episode, especially the TARDIS on the motorway scene, and a number of humorous scenes throughout the show. There were some great lines and great ideas.

On the downside, because this episode was for entertainment purposes, there were far too many holes in the plot for my liking. Okay, they aren't really holes, just situations where there was no explanation for something.

How can Donna be dragged across space in an instant with Huon particles? How strong is the ship if it can't be liquefied by being at the centre of the Earth? If it is several hundred miles down, just the air pressure should kill them. If the hole was just dug by lasers, why didn't it collapse? Why was the spider in a ship above Earth when all the work was happening below? If 4.6 billion years of Earthquakes, meteor strikes, solar flares and a core temperature of millions of degrees didn't destroy the Racnoss ship, not to mention the pressure of billions of tonnes of rock, why did a few million litres of water do the trick? Why were there Segways under the Thames? Why did the Robots plant the Christmas trees when they had no idea that Donna would be there? How did they know that Donna would be on that street at that time to be able to find her to try to capture her? There are many others.

Even so, 8 out of 10 for a great romp.

Award-winning comedy actress Catherine Tate and Sarah Parish star alongside David Tennant in a special Christmas edition of the time-travelling adventure.

Bride-to-be Donna mysteriously vanishes as she prepares to marry her boyfriend Lance in a glittering ceremony on Christmas Eve. She suddenly appears, to her complete astonishment, in the Tardis with the Doctor.

As the Tardis races to get to the church on time, the Doctor and Donna are closely watched by the sinister figure of The Empress of Racnoss from her throne in her spaceship. It soon becomes clear that Donna is the key to an ancient alien plan to destroy the Earth.

David Tennant plays the Doctor, Catherine Tate plays Donna and Sarah Parish plays The Empress of Racnoss. 

A scene was shown at a concert in Britain and a fan has kindly uploaded it onto YouTube for all of us to see. Viral Marketing at its best. In the scene Donna gets into a taxi to go to her wedding after the Doctor drops her off and has to contend with an ATM spewing money. He realises that the taxi driver was an evil santa and runs to his TARDIS to chase after her. Donna meanwhile also realises this when the taxi doesn't stop at the church and so she takes the mask off to reveal an alien robot driver. All the doors and windows of the taxi are locked and she can't get out. She begins screaming just as a blue Police Box starts speeding and flying down the motorway towards the taxi.

No matter how serious the storyline Russell T Davies understands that a flying police box has too much levity (pun intended) and so saves it for comedy episodes such as Christmas Specials. I'm definitely happy with that and the flying Police Box is used to good effect in this scene.

Catherine Tate is a well known British comedian and so, while this episode will have some grating and jarring moments with the Doctor gritting his teeth every time he has to talk with Donna, the Bride, there are bound to be a lot of funny moments. 

The BBC has recently begun screening Christmas trailers which contain a number of scenes from the story. It looks like a lot of fun!