In The Grove, near Alton, Hants

The Mercedes pulls up at the porticoed front entrance of The Grove, its wheels crunching on the gravel.  Greaves helps Henry Latrom from the car and supports him as they enter the hallway.

Doctor James greets them effusively. 'Mr Latrom, Elizabeth, this is a great pleasure, as always.  And this must be young Mr Parry.  You are all very welcome.'

Creep, says Kirjava.

The efficient young woman escorts Will to his mother's room, where he finds her and Mary watching the mid-morning news.  For Elaine's sake, Mary says nothing about the way they have been treated.  Will and his mother are overjoyed to see each other, so Mary leaves the room and spends an entertaining hour talking about the theatre with the gorgeous actor she saw the night before, while his companion, not used to being ignored, flounces off to the bar (vegetable juices only).  'That's the first and last time I put a supermodel's nose out of joint,' thinks Mary, and smiles at the young man, who would like to play Hamlet at the Almeida Theatre in Islington next October.

Later, she speaks privately and urgently to Will.  'These are not good people.  They hurt me and they threatened to hurt your mother.'  She describes her treatment at the hands of the blue-coated young woman.

Will is outraged at what he hears, but there is a permanent overriding thought at the front of his mind.  The Knife!  These people have money and resources – he can see that.  They will repair the Knife for him – and then… Freedom!  Lyra!

He refuses to think about the hold that they have on him, or its nature.  Kirjava keeps her own counsel.

After a very good lunch, he is invited to join Henry and Lizzie in Doctor James's office.  He enters the book-lined room and his eyes are immediately drawn to the Knife, still broken, but assembled with all its fragments complete, on the desk before him.  He has assembled the Knife himself, many times, on his bedroom floor in Winchester.

'Mr Latrom, Lizzie, thanks for looking after my mother.'

'Is she happy here, William?'

'Yes.  I'm sorry, but Mary said they were a bit rough with her – Mary, I mean – last night.'  Will describes what was done to Mary in this office.

Henry Latrom frowns.  If Will knew Henry better, he would know that this signifies considerable anger in him.

'I will speak to Doctor James about it.  Thank you for telling me this, William.  Now, do you have any questions for me, or Elizabeth?'

Will thinks.

'Yes, I've got one or two.  First, is there a forge here?  Where are we going to fix the Knife?  I have to be there when it's done, you know.  I was before.'

Again, Will has said more than he meant to say.  He tells them all about Iorek Byrnison and the brush-wood fire that he used to mend the Knife in the mountains.

'I see.  And your other question?'

'Well, it's this.  You say you're close to dying, but it's only been two years since the angels began closing the windows.  Now, my father lived for ten years in your world, and he was able to hike across mountains, while you need help to walk.  I'm sorry, but why is this?'

'William, I can answer both questions.  In fact, as you will see, both questions have the same answer.

'You may remember that my late brother Charles took an interest in experimental theology – physics, as you know it – and was involved in Dark Matter research in this world and our own.  It was one of the ways in which we encouraged commerce between the worlds.  The Knife, as you know, is connected with Dust – or Dark Matter – and derives many of its properties from it.  Charles would talk to me about it at inordinate length, sometimes.'  Henry sighs.

'Did you ever wonder about the properties of the windows you opened with the Knife?'

'No, not really,' replies Will.

'There doesn't seem to be anything elaborate or complicated about them, does there?'

'No – they're just windows.  You walk through them, and you're somewhere else.'

'And yet, they perform the amazing feat of allowing you to pass from one world to another.  Think about it, William.  Each world has its own special properties – some worlds are populated, some are not.  In some worlds, humans have daemons – full, visible daemons with a physical presence – in others, they do not.  What about the Gallivespians?  Could such tiny creatures have been created in your world; or mine?  No – in our worlds, such small beings would not have large enough brains to function as humans.'

'But they were human!'

'Yes, they were.  What I'm trying to get at, William, is this:  In all your travels between the worlds; you could live, eat, drink and breathe equally well in each one, couldn't you?'

'Yes, I suppose so.'

'But is that not incredibly unlikely?  The very composition of matter itself is different in each world.  Your body – and mine – should not be able to exist in an alien world.  And they could not – if it were not for the Knife, and the properties it grants to the windows it creates.

'When you pass through a Knife-created window, your body itself is changed in such a way as to make it compatible with the world that it has entered.  Your body changes, but your daemon, which is a metaphysical creature, does not.  That is why your body, to begin with, is unharmed by the transition from one world to another.  It is also the reason why your daemon begins to die the moment you enter a different world from the one in which she was born.

'That is the first point I wanted to make.  The window-changes are not symmetrical.  Your father's daemon, which only attained physical form in my world, had a lifespan of ten years when she moved from your world to mine.  But, due to the different properties of our worlds, my daemon, and Lizzie's, can only live two years at the most when they travel to yours.'

'I think I see what you mean,' says Will.  'Some people can live longer in some worlds than in others.'

'Yes, that is correct.  But they can only achieve their full natural lifespan in their own world.

'The second point concerns the Knife.  I have said that when you pass through a window, the properties of your body change to match the world you enter.  The same is true of the Knife.  When it was originally made by the philosophers of the Torre Degli Angeli, they employed a furnace which was, without their knowledge, powered by the decomposition of hydrogen atoms.  In another world, however, a simple charcoal fire created enough heat to allow it to be re-forged by the armoured bear Iorek Byrnison.

'In this world, no ordinary furnace can melt the metal of which the Knife is made.  It must be exposed to the powers of Heaven and Earth acting in concord.  There is a place not far from here where the Earth-Current and the Sky-Fires meet, and it is there that we must take the Knife tonight.

'Until then, enjoy the facilities of The Grove.  Lizzie will show you round.  You may see some people here whom you recognise – from films or newspapers, maybe.  They have come here for privacy.  Please respect it.'

Lizzie and Will leave Doctor James's office.  Henry Latrom sends the efficient blue-coated young woman to bring Doctor James to him.