The episode opens with Freema walking down Charlotte Street on the phone having her whole family ring her one by one on the way to work. It quickly establishes her disfunctional family and establishes her in the role of peacemaker. A brief cameo appearance of her father in a convertible, wearing leather and holding a blonde establishes his mid-life crisis situation but this is quickly forgotten as the Doctor suddenly appears, makes a cryptic comment about his tie and vanishes into the crowd.

On the way into the hospital she runs into a fully leathered and helmeted figure (a slab) who ignores her. She soon sees two of them.

She joins a group of interns looking into why a patient had a salt deficiency, being questioned by the director of the hospital.

Then she sees the Doctor lying in one of the beds. She asks him directly how he could speak to her about ties and then already be in bed at the hospital. He says it wasn't him.

She discovers he has two hearts. He winks at her and she doesn't say anything about it.

Her sister attempts to visit her when the whole hospital is surrounded by a thunderstorm and upwards rushing rain. Suddenly, in a blink of an eye and some shaking, the hospital is sitting on the moon.

Martha tries to explain to an Indian woman that the air is being held in by something and the Doctor appears. Martha and the Doctor head off to find a verandah to find out why the air is still there.

On Earth there is just a gaping hole in the ground where the hospital once stood, not far from a blue Police Box.

Martha and the Doctor discover a force field just as the Judoon ships arrive - intergalactic Police for hire. They're after an escaped prisoner and arrive in giant tower block style ships, then stomp their way through the force field into the hospital to catalogue everyone.

It is the Judoon who have brought the hospital to the moon so that there isn't any problem with legal jurisdictions.

Using scanners and a black marker they scan everyone and mark them, looking for a non-human.

The Doctor and Martha exchange info on the verandah, trying to work out the problem.

Meanwhile the old lady with the salt problem turns out to be some kind of vampire and attacks the director of the hospital, sucking his blood. She uses it to disguise her true nature so that, when the Judoon eventually scan her, she is considered to be human.

Unfortunately Martha stumbles on her blood sucking plan and she and the Doctor are chased by the slabs. They go into the X-ray room and the Doctor uses his sonic screwdriver to increase the power output to about 5000 percent. Martha helps him fry one of the slabs. The sonic screwdriver is equally fried.

Unfortunately the Judoon discover him and believe he must be the plasmavore so they chase him. He kisses Martha (a genetic transfer) which, when the Judoon find her, slows them down as they try to analyse the fact that she has alien DNA on her.

This gives the Doctor time to talk to the plasmavore and convince her he's just a stupid human so that she would suck his blood. His hearts stop as the Judoon break in. With the help of Martha the Judoon realise that the old woman is the alien they're looking for and then destroy her.

But the air is running out and with her last breathe she manages to bring the Doctor back to life before collapsing unconscious along with the thousands of other hospital staff and patients.

The plasmavore had created a magnetic overload which was about to destroy the Earth. The Doctor has to disable it. He does, just in time, and the Judoon return the hospital to Earth.

The Doctor disappears and Martha heads off to her brother's 21st.

But it doesn't end there. There's a fight at the party and the family split up outside. Martha is left alone until the Doctor appears. Martha is introduced to a blue Police Box and doesn't believe it can travel in time until the Doctor disappears and reappears, concluding the cryptic sentence about ties that he said to her before she went to work in the morning. She realises that this is the point that he went back in time to speak to her.

She joins him for 'just one trip' in the TARDIS.

I enjoyed it but I really don't know why Russell T Davies has an obsession with hospitals. Is it because our hero is called the Doctor?

Season 1 had a hospital story, as did Season 2.

Unfortunately there are a number of holes in this story.

If the Judoon took two days to build up enough plasma force to take the hospital to the moon because they were searching for an alien, how did they know the alien would be in the hospital 2 days before?

How can the plasmavore be protected from the massive magnetic energy wave that would destroy the brain stems of all people on half of the Earth. Does this mean she didn't have one? And how could she create so much energy from the limited amount of power a hospital, probably running on generators, would have?

Just because the hospital is returned to its hole in the ground, doesn't mean all the cables are going to automatically fit together again.

It must be an amazing hospital if there were no cardiac patients or patients in the middle of surgery. And it was also fantastic that the generators kept working on the moon.

Moon dust has been proven to be lethal. Judoon walking across the moon and stomping through a hospital without cleaning themselves up first should have caused a lot of problems.

If all the blood was sucked out of the Doctor, why didn't he regenerate?

I'm sure you'll find other holes. Still, the adventure was a lot of fun and Martha is a worthy addition as the 21st, 22nd or 23rd female companion to the Doctor. (If you're counting Dalek Master Plan and the Christmas Invasion)

7 out of 10 for the story. 10 out of 10 for Freema!

David Tennant returns to his role as the Doctor and meets his brand-new companion in the highly anticipated third series of Russell T Davies's Doctor Who.

For Martha Jones, a medical student in Central London, an ordinary day turns into a nightmare when her entire hospital is transported to the Moon. There, she has to battle the Judoon and outwit a blood-sucking Plasmavore – but can she trust a mysterious stranger called the Doctor?

David Tennant plays the Doctor and Freema Agyeman plays his new assistant, Martha Jones. Russell T Davies is also the executive producer. 
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A period of time after the adventures in The Runaway Bride, medical student Martha Jones finds a mysterious stranger known as Doctor John Smith in one of her Royal Hope hospital beds. Shes finds that he has two hearts. (So, similar to Auton Invasion with Jon Pertwee and The Telemovie with Paul McGann) 

Word has it that she did pass him on the way to work that morning, though. And we do get to see her family along the way) Suddenly the hospital is transported to the moon by a shape shifting alien on behalf of the Judoon, a race of Rhino-like Police.

Like stormtroopers they burst into the hospital.

The Doctor needs to perform a genetic transfer and the easiest way to do that is with a passionate kiss with Martha Jones. She gets to do it again later when he's dying and she needs to give him mouth to mouth resuscitation. Who's the lucky one?
Questions: Are these Lance Parkin's Rhino aliens - The Onihrs - from Trading Futures? Should we read this book to get a bit of history about them first? From the picture they look the same. Does Lance know this?