Enigma

of it all. Don't you find?'
    'I suppose so.' Oh, do get on with it, thought Jericho, stabbing at a couple of crumbs. Just sack me and leave. Logie made a contented sucking noise through his pipe, then said quietly: 'You know, we've all been terribly worried about you, Tom. I do hope you haven't felt abandoned.'
    At this unexpected display of concern, Jericho was surprised and humiliated to find tears pricking at his eyes. He kept looking down at the carpet. 'I'm afraid I made the most frightful ass of myself, Guy. The worst of it is, I can't remember much of what happened. There's almost a week that's pretty well a blank.'
    Logie gave a dismissive wave of his pipe. 'You're not the first to bust his health in that place, old thing. Did you see in The Times poor Dilly Knox died last week? They gave him a gong at the end. Nothing too fancy—CMG, I think. Insisted on receiving it at home, personally, propped up in his chair. Dead two days later. Cancer. Ghastly. And then there was Jeffreys. Remember him?'
    'He was sent back to Cambridge to recover as well.'
    'That's the man. Whatever happened to Jeffreys?'
    'He died.'
    'Ah. Shame.' Logie performed a bit more pipe smoker's business, tamping down the tobacco and striking another match.
    Just don't let them put me in admin, prayed Jericho. Or Welfare. There was a man in Welfare, Claire had told him, in charge of billeting, who made the girls sit on his knee if they wanted digs with a bathroom.
    'It was Shark, wasn't it,' said Logie, giving him a shrewd look through a cloud of smoke, 'that did for you?'
    'Yes. Perhaps. You could say that.' Shark nearly did for all of us, thought Jericho. 'But you broke it,' pursued Logie. 'You broke Shark.'
    'I wouldn't put it quite like that. We broke it.'
    'No. You broke it.' Logie twirled the spent match in his long finger. 'You broke it. And then it broke you.'
    Jericho had a sudden memory-flash of himself on a bicycle, under a starlit sky. A cold night and the cracking of ice.
    'Look,' he said, suddenly irritated 'd'you think we could get to the point here, Guy? I mean, tea in front of the college fire talking about old times? It's all very pleasant, but come on -'
    'This is the point, old thing.' Logie drew his knees up under his chin and wrapped his hands around his shins. 'Shark, Limpet, Dolphin, Oyster, Porpoise, Winkle. The six little fishes in our aquarium, the six German naval Enigmas. And the greatest of these is Shark.' He stared into the fire and for the first time Jericho was able to have a good look at his face, ghostly in the blue light, like a skull. The eye sockets were hollows of darkness. He looked like a man who hadn't slept for a week. He yawned again. 'You know, I was trying to remember, in the car coming over, who decided to call it Shark in the first place.'
    'I can't recall,' said Jericho. 'I've an idea it was Alan. Or maybe it was me. Anyway, what the devil does it matter? It just emerged. Nobody argued. Shark was the perfect name for it. We could tell at once it was going to be a monster.'
    'And it was.' Logie puffed on his pipe. He was starting to disappear in a bank of fumes. The cheap wartime tobacco smelled like burning hay. 'And it is.'
    Something in the way he delivered that last word—some slight hesitation—made Jericho look up sharply.
    The Germans called it Triton, after the son of Poseidon, the demigod of the ocean who blew through, a twisted seashell to raise the furies of the deep. 'German humour,' Puck had groaned when they discovered the code name, 'German fucking humour But at Bletchley they stuck to Shark. It was a tradition, and they were British and they liked their traditions. They named all the enemy's ciphers after sea creatures. The main German naval cipher they called Dolphin. Porpoise was the Enigma key for Mediterranean surface vessels and shipping in the Black Sea. Oyster was an 'officer only' variation on Dolphin. Winkle was the 'officer only' variant of Porpoise.
    And Shark? Shark was the operational cipher of the U-boats.
    Shark was unique. Every other cipher was produced on a standard three-rotor Enigma machine. But Shark came out of an Enigma with a specially adapted fourth rotor which made it twenty-six times more difficult to break. Only U-boats were allowed to carry it.
    It came into service on 1 February 1942 and it blacked out Bletchley almost completely.
    Jericho remembered the months that followed as a prolonged nightmare. Before the advent of Shark, the cryptanalysts in