DOCTOR WHO IN DETAIL

After the previous adventure the TARDIS, instead of returning to Earth, lands in London, 1814, during a time when the Thames had completely frozen over. On the ice there is a market and a fair. This is Bill's first trip into the past, and she is worried about making a change that could affect the future. She talks about the butterfly effect, and the Doctor tells her about her friend Pete - who stepped on a butterfly and this meant he was never born. Which is why Bill can't remember him. Bill is fairly certain the Doctor is joking.

Whilst there is entertainment on the Thames no-one hears the creature that is shackled below. Whilst trying out different activities Bill notices green lights under the ice. The Doctor has also noticed the lights, and was waiting for Bill to catch up. A girl, Kitty, distracts the Doctor, allowing a boy, Spider, the chance to steal the sonic screwdriver. The Doctor and Bill chase Kitty and Spider to a quieter part of the ice, and the lights follow. Spider stops when he sees the lights surrounding his feet. The Doctor and Bill arrive in time to see him fall through the ice. The Doctor is happy he has his sonic screwdriver back, but Bill is upset; this is the first time she has seen someone die.

The Doctor asks Kitty to show him and Bill where she and the other urchins are staying. The Doctor offers pies, previously stolen from a pie seller, to the urchins. The Doctor asks them about the frost fair. Dot tells the Doctor that a bad man paid Kitty to lure people out on to the ice. Dot tells the Doctor that the man has a tattoo on his hand, but they don't have a means to get in contact with the man.

The Doctor has a plan. He knows there is something under the ice that eats people, so his plan is to get eaten. Using two diving suits the Doctor and Bill venture out onto the ice. The heavy suits attract the lights. Bill is dragged under the ice, and the Doctor is able to jump in after her as the ice hole closes. Under the ice they see the source: fish that havre a tentacle with a light. They also see the huge creature chained to the river bed.

On the bank of the Thames Bill asks a man if he has seen anyone acting suspiciously since the start of the freeze. He tells Bill and the Doctor about a workhouse up river where the dredgers work. Using psychic paper the Doctor is able to bluff himself and Bill inside. It looks as though the dredgers are making mud bricks. But as the creature is about a mile long, and the head of the creature is a mile away, the bricks are probably not made from mud.

The bricks are destined for the steel mill where they are used as fuel. It burns a thousand times longer than coal, and hotter than can be measured. It even burns under water. Knowing this the Doctor and Bill visit the workhouse owner - Lord Sutcliffe. The first thought is that Lord Sutcliffe may be an alien, with a creature than can produce fuel for interstellar travel. After attacking Sutcliffe for racism towards Bill the Doctor realises Sutcliffe is human.

When asked about the creatutre Sutcliffe says his family has always known about it, and that there are no records about how many people it has killed. Sutcliffe believes his heritage makes him more important that other people - including the people that have been killed by the creature. Sutcliffe decides to bring his plan forward, and takes Bill and the Doctor to a tent on the ice where they are bound to fireworks. Sutcliffe plans to use the fuel to cause an explosion that will kill people on the ice, and make it look like a firework display gone wrong.

Using the sonic screwdriver the Doctor and Bill are able to get free, and Bill tells the Doctor to save the creature. The Doctor works on the firework controls whilst Bill gets everyone off the ice. When Sutcliffe sees people leaving the ice he sets up a plunger to detonate the explosives. But when he pushes it there is no explosion, at least not above the Thames. Below the Doctor has attached the explosives to creature's chains. As the creature, now free, swims away Sutcliffe falls into the Thames.