Ken felt a queer thrill. There was something uncanny in the thought that they were spinning along, sixty feet below the sea-level, cut off from all the living world.

'Pass the word the commander wishes to see Carrington,' came a voice.

'Lootenant Strang wants you,' said Williams. 'Go right aft. Sentry'll show you. And go careful, mind you. Submarines ain't the sort o' shops for foot races.'

Ken went cautiously back past the amazing tangle of spinning, whirling machinery. Where the long interior narrowed to the stern hung a thick curtain. The sentry silently parted it, and Ken found himself in the officer's quarters of G2. They were as plain as the steerage on a liner. Just two bunks and in the middle a table at which Lieutenant Strang sat, busily writing.

He glanced up as Ken entered, and, saluting, stood to attention. Ken noticed, with inward approval, the strength and intelligence in the clean-cut features of the commanding officer.

'Feeling better, Carrington?'

'Quite all right, sir, thank you.'

'Had breakfast?'

'Yes, sir.'

'I want to hear what you've been doing. Let's have the whole yarn.'