She nodded and he followed her out. The lights along the roof of the tunnel were kept on night and day, and in all the cabins there were pilot lights that gave out a faint blue radiance, like those in the sleepers of International Pullman cars. Very quietly they walked down two-thirds of the length of the tunnel, then she halted and followed his instructions. The door of the office was not locked and he was in there a good ten minutes. To her it seemed an interminable time as she strained her ears for approaching footsteps, and her eyes into the semi-gloom behind her. But at last he emerged, and closed the door gently after him.

Taking her arm, and still walking softly, without uttering a word he led her back to the dining cabin. There, in the brighter light, she saw that his normally ruddy face had gone a queer shade of grey, and that his black eyes held a murderous glint.

'Well,' she asked in a whisper.

He sat down heavily, and muttered, 'What I thought a crazy idea was right. It's all worked out there. He's aiming to put it on Moscow.'

At first Mary did not realize the full implications, so she said, 'I can't help feeling sorry for the Russians; but thank God it's not London.'

For a moment he stared at her then, his voice still low, he broke into a tense spate of words, 'Be your age, woman! The Russians will take it that the West launched the rocket at them. They'll not wait to ask questions. They'll think we've tried to shoot 'em sitting down. Before what's left of Moscow's gone up in smoke they'll press the button. Within twenty minutes New York, Washington, Pittsburg, Detroit will be just heaps of poisonous ruins - and London too. The West will react with all it's got; land-based rockets, rockets from subs and cruisers, H bombs from aircraft. Russia's got subs, cruisers and long-range aircraft too - plenty. I'd give it three days, and every city west of a line Urals, Persia, India will have had it. Tens of millions dead, hundreds of millions dying; the whole of civilization as we know it to hell and gone.'

'Oh God!' she breathed, 'Oh God! Somehow we must stop it!'

'That's easy to say; but you know the man we're up against. I'd never be able to argue him out of anything he's set on.'

'But why, why does he want to do this frightful thing?'