His confidence had ebbed somewhat by the time he reached the ground floor. Through the window beside the main door he could see nothing beyond an empty stretch of paving, the light of the porch lamp leaching away beyond that into velvety shadows. He took several deep breaths to calm himself. By rights he should be at home in Chiswick, sleeping soundly after an undemanding day in Whitehall. Instead he was in Hamburg, behaving like a Cold War spy making a pick-up from a dead-letter drop in the middle of the night.

He finally tired of his own apprehensiveness and yanked the door open. Nothing moved on the street. No shadow in human form loomed into view. The mailboxes were only a few steps away. He reckoned the smallest key on the bunch would fit the lock on Frau Straub’s box. And so it proved.

Inside was a thickly filled brown envelope. He lifted it out, closed the box and retreated indoors. There was neither name nor address written on the envelope. It had clearly been delivered by hand. It had also been left unsealed. Eusden pulled back the flap. A chunky wad of banknotes met his surprised gaze. The topmost note was €100. So were the next few. He gasped, shoved the envelope into his pocket and started up the stairs.

‘Where the hell have you been?’ demanded Marty when Eusden walked back into the flat. ‘I come out of the shower and you’ve vanished into thin air.’ He cut a bizarre figure in white shirt, hound’s-tooth-patterned sweater and twill trousers that finished an inch or two above his trainers. He had a beer in one hand and a hunk of cheese in the other. His hair was still wet and he had a towel looped round his neck to catch the drips. ‘Plus you switched the lights off. Are you trying to spook me?’

‘We had a phone call. Announcing a special delivery.’ Eusden took the envelope out of his pocket. ‘I’ve just been down to collect it.’

‘What is it?’

‘Money. Rather a lot, by the look of it.’ Eusden dropped the envelope on to the coffee table. ‘See for yourself.’

Marty sat down in the armchair and plonked the bottle of beer on the table. He put the cheese in his mouth and devoured it as he fanned the wad of notes, then counted them. ‘Bloody hell,’ he said when he had finished. ‘There’s ten thousand here. What did the caller say?’

‘“Check the mailbox.” Nothing else.’

‘It has to be from Werner.’

‘You think so?’

‘No one else owes me a cent, Richard. This is my pay-off. A pittance compared with the profit he’s hoping to make. But enough, he’s calculated, to persuade me to give up and go home.’

‘And will you?’

Marty took a swig of beer and sat back in the chair. ‘It’d make the time I’ve got left more comfortable than it’s likely to be otherwise. And it’d make my landlord a happy man.’

‘But it wouldn’t pay the Swiss specialist’s bill, would it? Not from-’ Eusden stopped. The incomprehension on Marty’s face told him what he should already have guessed. ‘There is no clinic in Lausanne offering a revolutionary treatment, is there?’

‘’Fraid not. Nice idea, but… no.’

‘Straub said that’s what you needed the money for that you were going to make from selling the contents of the case.’

‘Just as well he was lying, then. Since this is all the money I’m likely to see now.’

‘Are you saying you’ll settle for that?’

‘It’d be the smart move, I guess. What he put me through here was the stick. This is the carrot.’

‘You’re going to let him get away with it?’

‘Sit down, Richard. You look like a man with a mission. It doesn’t suit you.’

Eusden sat down. ‘You promised me an explanation, Marty.’

‘Yeah, but this money… changes everything.’

‘How?’

‘It means I don’t have to go away empty-handed. Terminal illness alters your perspective on life, take my word for it. I could have my own fortnight in the sun now. Several fortnights, in fact.’

‘And that’s enough?’

‘What d’you want me to say? At heart, I’ve always been a hedonist. It makes no sense to put you in the picture if we’re not going to do anything about it.’

‘We?’

‘I can’t go on alone, that’s for sure. All in all, it’s probably best to end it here. Take the air fare back to London out of this lot. You’ll be behind your desk again by Wednesday morning, sipping a coffee freshly brewed by your curvaceous PA, glad your excursion to Hamburg is just a brief, bad memory. Then, in a few weeks, if you feel like it, come over to Amsterdam and we’ll spend some of Werner’s dosh on a pub crawl.’

‘You seem to have forgotten you owe me most of this in bail money.’

‘Ouch.’ Marty’s expression suggested he really had forgotten. ‘OK. It’s a fair cop. You have first call on it, no argument. Help yourself. Don’t worry about me. Dying penniless is a piece of cake.’

‘I’m not interested in the money, Marty. I’m interested in the truth. You surely don’t think you can get away with stonewalling me like this, do you?’

‘Why not? You’re not planning to tie me up again, are you?’

‘I knew Clem almost as well as you did. What did he have that a creep like Straub could sell now for a small fortune?’

‘Not so small, in all likelihood.’ Marty smiled wryly. ‘Sorry. It really is best if I say nothing.’

‘How did you meet Straub?’

‘Our research interests… coincided.’

‘Research into what?’

Marty’s smile assumed a pained fixity. He did not reply.

‘Clem came to Hamburg once, didn’t he?’

‘Did he?’

‘You know he did. While I was on the train, I remembered him talking about it. One of his hush-hush Special Branch missions, some time after the War. We used to think he made them up. I’m guessing he didn’t make this one up.’

‘Guessing? You certainly are.’

‘Tell me I’m wrong, then.’

More silence. Marty’s smile faded into blankness.

‘Why did you come to this flat on Sunday evening?’

‘Werner said there was something here that might interest me. He was lying, naturally.’

‘But why were you taken in?’

‘I’m a gullible guy.’

‘Come on, Marty. You thought it was likely to be true. Why? Something to do with Straub’s father, maybe? What did he do for a living?’

‘Journalist. Worked on the local daily. The Hamburger Abendblatt.’

‘At the time of Clem’s visit?’

‘Probably. If there was a visit.’

‘What was in the case?’

‘You’re not going to give up, are you?’

‘No, I’m not.’

‘Oh God.’ Marty rubbed his face and took another gulp of beer. He gave Eusden a long, studious stare. ‘You’ll regret getting involved in this, y’know, you really will.’

‘I’m already involved.’

‘No. Affected by it. But not involved. There’s a big difference. I’m not chasing a quick buck, as Werner seems to think. I’m chasing… meaning, I suppose. When the doc told me I was on the way out, I considered how I ought to spend the small amount of time I have left. More of the same in Amsterdam. Or something… different. That’s when I remembered Clem’s attaché case.’ (Marty had always referred to his grandfather as Clem, making him seem more of an old friend than a relative.) ‘It ended up with Aunt Lily after he died. When I eventually got round to visiting her, she said I ought to have it. She thought I’d be able to make sense of the contents. I took a look. I couldn’t work out what they amounted to. So, I… asked her to hold on to the case for me. She made a point of locking it and giving me the key. She had an inkling, I think, that it was… important. I couldn’t see how at the time, but I do now. So does Werner.’

‘What did it contain?’

‘It’s a long story. And I’m dog-tired. Neither of us is thinking straight. There might be a way, if you help me, to get at the truth, despite losing the case. I’m just not sure. The Foreign Office would have to do without you for a while, though. You’d have to… make a commitment. So, sleep on it. There’s a single bed in the spare room. As the invalid, I’m claiming old Mother Straub’s double. Let’s get a few hours’ kip. Then, in the morning, if you still feel the same way I’ll tell you everything.’ Marty summoned a weary grin. ‘Every last incredible detail.’