Martha's sister Tish works there and gets them into the investor's party, along with Martha's brother and mother.

Martha makes a comment to the Doctor that he looks a bit like James Bond in his tuxedo. He's quietly pleased with the compliment!

The Doctor gets to meet Mrs Jones and she is not impressed with him at all.

76 year old Professor Lazarus starts the experiment which has him getting into something similar to the old The Fly movies and being surrounded by sonic waves. The machine overloads and the Doctor rushes over to the controls to stop it from exploding. Lazarus emerges looking in his early 30s.

(Note that when this machine is turned on again later in the episode, there is no mention of the power cable being pulled but the assumption is that the monster reconnected it)

Lazarus is very hungry but something is wrong with his body. He gives Martha a kiss on the hand then heads upstairs for a discussion with his wife.

Martha and the Doctor use the DNA Lazarus left on Martha's hand to investigate it and it shows that he's still mutating.

Upstairs Lazarus turns into a monster and absorbs his wife's life energy. (Hmm, no catalytic extraction chamber from Weng Chieng needed here.)

Back to normal downstairs and Lazarus invites Tish to go to the roof with him. Now that he's young and attractive Tish is interested.

Hmm. The Fly, Jekyll and Hyde, what else? There's all sorts of themes in this. Evil genius millionaire trying to take over the world but only a man in a tux can stop him. etc.

Martha and the Doctor are trying to find him but they miss each other at the lifts. They run downstairs, meet the family, then run back upstairs and rescue Tish from the Monster Lazarus just in time, just after he talks about a nearby Cathedral.

You know, the monster does have a hunch back.  I can see a Notre Dame theme coming up. 

In escaping him, building lockdown is activated and everyone is trapped inside. The monster attacks the guests, absorbing one of them. Martha gets them all out with the Sonic Screwdriver while the Doctor acts as bait and attracts the Lazarus monster. He gets him into one of the laboratories with gas taps and turns some of them on, then causes an explosion which has him flying out of the door. Then Martha runs into the Doctor to return his sonic screwdriver.

Unfortunately the monster easily survives the explosion and runs after them. The Doctor and Martha hide in the rejuvenation machine. (Hmm, I just remembered the Leisure Hive) The monster turns it on as the Doctor madly tries to reverse the polarity. The shockwave knocks Lazarus out and he's believed to be dead. What, with another 15 minutes or so to go?

"It really shouldn't take that long to reverse the polarity. I must be a bit out of practice"

While all this excitement is going on a representative from Harold Saxon informs Martha's mother about the Doctor. We don't hear what he says but she's horrified.

When he comes out Martha slaps the Doctor's face. 

"All their mothers. Every time!"

There's a bang and the Doctor, Martha and Tish discover the ambulance that was carrying Lazarus is open and the occupants dead. They go into the cathedral and find Lazarus at the front.

A final chat with the Doctor before Lazarus changes again and prepares to eat. He turns into the monster and chases Tish and Martha up to the bell tower (!!!) The Doctor heads to the organ to perform some phantom of the opera music while Martha and Tish keep the monster busy.

The Doctor amplifies his sonic screwdriver through the organ and shocks the monster into falling to the ground below. Where are the bells, the bells?

Well, lots of really great scenes, excellent special effects and action. This is much better than last week's story. I really enjoyed this one enough to want to watch it again.

My only quibble was with the monster. It really would have looked better without a human face because the face really didn't look real enough. Having said that it was a great creation and I'm sure, even with Lazarus dead and returned to his old self, a monster like it is likely to return. The machinery is still there. And there was a "The Fly 2!"

8 out of 10

P.S. At the end of this episode when screened in the UK was a trailer featuring scenes from all upcoming episodes. Excellent stuff. 

Martha returns home as Russell T Davies's Doctor Who continues. Could this be the end of her travels with the Doctor? When she discovers her family is caught up in the scheming of Professor Lazarus and his Genetic Manipulation Device, it becomes a fight for survival, as human DNA twists into monstrous form.

David Tennant plays the Doctor and Freema Agyeman plays his companion Martha Jones. Thelma Barlow and Mark Gatiss guest star.