reduction.
- Yes, sir.
- At full reduction.
- Right.
- That air feels good.
- Yes.
- Are you all right?
- Yes, I'm OK.
Mr Grant, tell them the Proteus is on power.
- Proteus on power, sir.
- OK, Don, it's all yours.
Phase four.
Elevate zero module.
Check thermal blanket.
Tracking.
Contact Proteus.
- Stand by for injection.
- Right.
Inject.
Tracking post.
The medieval philosophers were right.
Man is the centre of the universe.
We stand in the middle of infinity,
between outer and inner space.
And there's no limit to either.
I never imagined
it could be anything like this.
- No, I always thought it was nothing but red.
- Only to the naked eye.
Those corpuscles carrying oxygen
give the stream its colour.
The rest of the plasma's
very much like sea water.
- An ocean of life.
- End to end, 100,000 miles long.
Dr Duval?
What could those be?
That looks like
the molecular structure of proteins.
I don't agree.
- We should stop and investigate.
- I'm afraid we haven't time.
Captain, keep your present heading
until we're in the clear.
Arterial wall to the left.
- What's our speed?
- 15 knots.
You should reach
the main branching artery in two minutes.
Keep the wall at this distance
when you turn.
That should bring you safely
into the middle of the branch.
- Captain, correctyour course and speed.
- She won't respond. We're in a current.
- That isn't possible.
- Not in a sealed vessel like an artery.
There's something wrong with your controls.
No, it's a current. It's too strong.
I can't seem to break out of it.
Whirlpool. Strap yourselves in.
Anyone hurt?
Cora?
I'm all right. Thank you, Doctor.
Where are we?
The corpuscles are blue.
Captain, what's your compass heading?
Proteus off course.
They've... they've crossed over
into the jugular vein!
That can't be. There's no direct
connection between the two.
Well, normally not.
Unless there's an arteriovenous fistula.
A what?
It's a forced joining of a vein and an artery.
It must have happened when Benes was hurt.
Yes, a fistula too small
to show up in the tests.
- But big enough for us.
- Can you head back into the artery?
No, we can't fight that current.
It's impossible.
Well, try not to drift down any further.
I'll do what I can.
Is there an alternate route?
We can go forward on this course but...
that means going directly through the heart.
No, we can't do that either.
We decided in the briefing.
This craft couldn't stand the turbulence.
It would be a hundred times worse
than the whirlpool.
That's just dandy!
We can't go forward and we can't go back.
There's only one thing we can do.
Call off the mission.
We've no choice. We've got to take them out.
No. We've still got 51 minutes. Leave 'em in.
But it's hopeless.
They can't go back and they can't go on.
There's no choice but to remove them.
Not until the last second. We gotta
think of something to save the situation.
Proteus reports trapped in venous system.
Requests removal, sir.
Well, there it is.
What do I tell them, General?
Doctor...
Without killing him,
how long could we stop his heart?
- The less time the better.
- I know, but what's the maximum?
In his comatose state and
everything slowed down,
no more than 60 seconds.
At top speed, adjusting distance
for degree of miniaturisation,
that sub should get through the heart
in exactly 57 seconds.
That's only three seconds to revive him.
What are the problems involved
in stopping the heart?
Nothing - compared with starting it up again.
We're wasting time. Let's get on with it.
Message to Proteus.
- Cardiac red alert.
- Maintaining maximum speed,
the sub should get through the heart
in 57 seconds.
This will allow us three seconds to spare
in which to revive him.
To minimise the turbulence
we will have to arrest the heart.
Prepare for cardiac shock. Remove the radar.
The Proteus will proceed
to the entrance of the right atrium,
at which point the heart will be