Enigma

lately.'
    He passed a hand through his thinning hair and Jericho noticed for the first time that he'd turned quite grey. So it's not just me, he thought, it's all of us, we're all falling to pieces. No fresh air. No sleep. Not enough fresh food. Six-day weeks and twelve-hour days . . .
    'We were still just about ahead of the game when you left,' said Logie. 'You know the drill. Of course you do. You wrote the bloody book. We'd wait for Hut 10 to break the main naval weather cipher, then, by lunch time, with a bit of luck we'd have enough cribs to tackle the day's short weather codes. That would give us three of the four rotor settings and then we'd get stuck into Shark. The time-lag varied. Sometimes we'd break it in one day, sometimes three or four. Anyway, the stuff was gold-dust and we were Whitehall's blue-eyed boys.'
    'Until Tuesday.'
    'Until Tuesday.' Logie glanced at the door and dropped his voice. 'It's an absolute tragedy, Tom. We'd cut losses in the North Atlantic by 75 per cent. That's about three hundred thousand tons of shipping a month. The intelligence was amazing. We knew where the U-boats were almost as precisely as the Germans did. Of course, looking back, it was too good to last. The Nazis aren't fools. I always said: “Success in this game breeds failure, and the bigger the success, the bigger the failure's likely to be.” You'll remember me saying it. The other side gets suspicious, you see. I said -'
    'What happened on Tuesday, Guy?'
    'Right-ho. Sorry. Tuesday. It was about eight in the evening. We got a call from one of the intercept stations. Flowerdown, I think, but Scarborough heard it too. I was in the canteen. Puck came and fetched me out. They'd started picking up something in the early afternoon. A single word, broadcast on the hour, every hour. It was coming out of Sainte-Assise on both main U-boat radio nets.'
    'This word was enciphered in Shark, I take it?'
    'No, that's just it. That's what they were so excited about. It wasn't in cipher. It wasn't even in Morse. It was a human voice. A man. Repeating this one word: Akelei'
    'Akelei,' murmured Jericho. 'Akelei . . . That's a flower, isn't it?'
    'Ha!' Logie clapped his hands. 'You are a bloody marvel, Tom. See how much we miss you? We had to go and ask one of the German swots on Z-watch what it meant. Akelei: a five-petalled flower of the buttercup family, from the Latin Aquilegia. We vulgarians call it columbine.'
    'Akelei? repeated Jericho. 'This is a prearranged signal of some sort, presumably?'
    'It is.'
    'And it means?'
    'It means trouble, is what it means, old love. We found out just how much trouble at midnight yesterday.' Logie leaned forwards. The humour had left his voice. His face was lined and grave. 'Akelei means: “Change the Short Weather Code Book.” They've gone over to a new one and we haven't a bloody clue what to do about it. They've closed off our way into Shark, Tom. They've blacked us out again.'
    It didn't take Jericho long to pack. He'd bought nothing since he arrived in Cambridge except a daily newspaper, so he took out exactly what he'd carried in three weeks earlier: a pair of suitcases filled with clothes, a few books, a fountain pen, a slide rule and pencils, a portable chess set and a pair of walking boots. He laid his cases on the bed and moved slowly about the room collecting his possessions while Logie watched him from the doorway.
    Running round and round in his head, unbidden from some hidden depth in his subconscious, was a nursery rhyme: 'For want of a nail, the horse was lost; for want of a horse, the rider was lost; for want of a rider, the battle was lost; for want of a battle, the kingdom was lost; and all for the want of a horseshoe nail . . .'
    He folded a shirt and laid it on top of his books.
    For want of a Short Weather Code Book they might lose the Battle of the Atlantic. So many men, so much material, threatened by so small a thing as a change in weather codes. It was absurd.
    'You can always tell a boarding-school boy,' said Logie, 'they travel light. All those endless train journeys, I suppose.'
    'I prefer it.'
    He stuffed a pair of socks down the side of the case. He was going back. They wanted him back. He couldn't decide whether he was elated or terrified.
    'You don't have much stuff in Bletchley, either, do you?'
    Jericho swung round to look at him. 'How do you know that?'
    'Ah.' Logie winced with embarrassment. 'I'm afraid we had to pack up your room, and, ah, give it to