Rejoining the Inspector, who all this time had been glumly waiting outside, Barney arranged for him to have the house kept under observation, on the off-chance that Lothar, or the Colonel, might return to it; then he collected his own car and accompanied the police cars back to Cambridge. On their arrival in the city the Inspector knocked up an hotel for Barney and, feeling that there was nothing more that he could do for the time being, he took a room in it.

By then it was close on three in the morning, and he had had a twenty-hour day, the last eight hours of which had been filled with constant strain and endeavour. Yet, tired as he was, he did not manage to get to sleep for over an hour after he had got into bed, because he was still so agitated about what might be happening to Mary.

He had left a call for seven o'clock. By a little after eight he was on his way to London, and well before ten he was in the office of C.B.'s P.A., declaring that he must see the Chief urgently as soon ns he arrived.

'He's already here,' the P.A. replied with a slightly sour grimace. 'He has been here half the night, and wrecked my Sunday by calling me up at eight o'clock to report for duty. But he is expecting you, so you can go right in.'

C.B. was seated at his desk, but for once there were no papers upon it; apart from a used coffee cup it was empty. As Barney entered Verney turned his head and asked quickly, 'Any news of the Great Ram?'

'News?' Barney repeated. 'Not since I telephoned. I was hoping that the police had picked him up.'

'No, you were wrong about his being on his way to London. I had Scotland Yard lay on everything they'd got, but to no purpose. My bet is now that he has again left England by air.'

'What makes you think that, Sir?' Barney asked with nervous sharpness.

Verney gave a wry grin. 'If you've got a flask on you, you'd better take a pull from it. About one o'clock this morning your new pal, Colonel Henrick G. Washington, left his base in an aircraft. With him he took a little souvenir. Can you guess what it was?'

'Not . . .' Barney's eyes widened, '. . . not an H bomb?'

'You've hit it, chum; or near as makes no difference. Actually it was one of the latest pattern U.S. nuclear warheads.'

'And Lothar went with him?'

'Everything points to that.'

'But Mary! Mary!' Barney's voice was an anguished cry. 'What have they done with her?'