thunder-clap! Any sound down there travels along the pipeline.'
Robson's theory seemed logical, but unconvincing.
'But this sound wasn't mechanical,' retorted van Lutyens.
There was no doubt that Robson was now on the defensive.
'All right!' he thundered. 'Suppose it wasn't mechanical. Suppose there is something in the pipeline, a fish or something. What d'you expect me to do about it?'
The Doctor was first to reply. 'Turn off the gas flow until you've had a chance to check.'
'Out of the question!'
'But Mr Robson,' pleaded van Lutyens, 'if something is inside the - '
Robson was adamant. 'We do not turn off the flow. And that's final!'
'Down another half, sir!' The Chief Engineer was tapping the pressure meter again.
Robson pushed him aside to look at the meter himself. 'It must be a mechanical fault!' he snapped. 'Get a couple of men in here, and double-check!'
'Yes, sir!' The Chief Engineer rushed out.
Van Lutyens wiped the sweat from his forehead, and took an anxious look at the pressure meter. The indicator needle was flickering perilously close to the red danger level.
'If you allow the pressure to build up much more in that pipeline!' said the Dutchman, turning to Robson, 'you'll blow the Control Rig sky-high!'
'And all of us with it,' warned the Doctor.
Van Lutyens stared defiantly straight into Robson's eyes. 'Just because you're too stubborn to turn off the gas!'
There was a delayed reaction from Robson, which seemed like hours to the crew who were watching tensely.
'So what d'you think it is then?' There was a restrained but acid calm in Robson's eventual reply. 'Some more of these creature things that hysterical girl is supposed to have seen?'
'Who knows?' answered the Doctor. His face revealed just the hint of a wry smile.
In the Control Hall, Price was showing Jamie and Victoria the lay-out of the communications system.
'You mean, this place supplies gas to the whole of the south of England?' asked Jamie, casting his eyes over the maze of computer monitors on the huge Cone structure.
'Not only England,' replied Price. 'Wales too.'
Victoria's face was illuminated by a succession of different coloured lights, flashing on and off all over the Cone. 'What are all these lights for?' she asked, looking totally bewildered.
Price nodded towards a computerised board. 'That's a plan of the entire Refinery Compound. Each light represents a remote-controlled camera that I can switch through to my own personal monitor if I want to check with a particular area.'
Jamie scratched his head, trying hard to take in all the technical information. 'What about these rigs they keep talking about?'
'The rigs are out at sea,' said Price. He was now looking up at the huge illuminated panel on top of the Cone. 'That panel up there shows the relative position of all of them.'
'What's the big one... there in the middle?' asked Victoria. She was referring to a large red-coloured oblong shape in the centre of the panel.
'That's our main Control Complex Rig, the nerve centre of the entire group. The other rigs feed her with the gas, and she pumps it through to us via the main pipeline.'
'How horrible to have to live out there in the sea all that time,'
said Victoria, bringing the conversation down to a more human level.
'And lonely.'
'Oh, I don't know,' said Price. 'Mr Robson spent nearly four years on one of the early rigs. He never came ashore once.'
'Aye,' said Jamie acidly. 'That accounts for quite a lot.'
Jamie had no sooner spoken when Robson himself came out of the Impeller Area. Van Lutyens and the Doctor were with him.
'Doctor! I need your help!'
The Doctor turned, to see Harris hurrying across the Hall from the compound entrance.
'It's my wife. She's very ill.'
'I'm sorry, Mr Harris,' said the Doctor awkwardly. 'You see I'm not really a - '
'Our own doctor is still out at Rig D. There's no one else I can turn to.' There was desperation in Harris's voice. 'You must come.
Right