The address that Gregor had given me was in one of the housing estates ringing Moscow. Rows of identical Brezhnev-era housing blocks had been built in what was once luxurious parkland, but was now littered with the debris of twenty-first century capitalism. The old symbols of the Soviet Union had been pried away, leaving irregular shadows on the crumbling concrete. Murals depicting the dignity of labour were now covered in graffiti. What was once meant to be a workers' paradise was now a place for the left-behind and the forgotten.

"You know about the Lost Cosmonauts?" Gregor has asked me.

"All hoaxes," I said. "Or misunderstood intelligence reports. The archives are clear."

"Well, what about the Found Cosmonauts?"

"The what?" I had a good knowledge of Cold War conspiracies, but this one was new to me.

Gregor smiled at me and handed me a piece of card. "Go here. Tell the man there that I sent you. And, if he won't talk to you, just tell him that it's about lightning."

So, here I was, climbing up five flights of stairs in a decrepit apartment block. I came out of the stairwell and into a dark corridor, full of the scent of boiled cabbage and mould. I found the door of the flat I was after and knocked. There was silence, then the sound of locks being fumbled open. An old man with tired eyes stared at me through the gap between the door and its frame. "Yes? What is it?" He sounded wary, hostile.

"I'm here to see ... ." I looked at the piece of card that Gregor had scribbled the details on. "To see Andreij Mikoyan."

"That is me. Now you know. But I do not know you. Go away."

The old man tried to push the door to, but my foot was in the way. "Gregor said that I was to talk to you about lightning."

The man stopped, opened the door, and glanced fearfully up and down the ill-lit, narrow corridor. It was empty, apart from the two of us. "In," he said in a voice that brooked no argument. "Now."

As he closed and locked the door behind us, I looked around Mikoyan's flat. It was small and decorated in primary colours in an attempt to relieve the gloom. A single lightbulb hung from a flex in the ceiling. In the corner, by a flatscreen television, was a two-ring electric hob. Low shelves were home to a collection of nick-knacks.

"What do you know about 'Lightning'?" Somehow, I could hear the capital letter.

"Nothing. But Gregor said it had something to do with you being a cosmonaut? I've never heard of any cosmonaut called Andreji Mikoyan."

"And nor has anyone else." The old man glared at me. "Tea?"

"Please."

Mikoyan went to the hob, put a kettle onto one of the rings, then started to assemble the tea things. "Lightning," he said. "It was a project that I was recruited into. A project to put armed stations into orbit to defend the Rodina against capitalist aggression." He snorted derisively.

"Like the Salyut armed stations?"

There was a crash as Mikoyan slammed the tray of tea things down onto a nearby table. "Toys," he spat. "Armed with aircraft guns. No wonder the Americans defeated us if that was the best that could be done." He stared at me. "You have a western accent. You are American?"

"British," I told him.

Mikoyan chuckled. "I like the British. You do not think you are morally superior because you are rich. You do not lynch negroes."

I took the proferred cupful of thick, black, aromatic tea. It was hot and sweet. "Good tea," I said.

"And you do not ask for milk."

I took another sip from the cup. Mikoyan pointed to a threadbare chair. "So, you want to know about Lightning?"

I sat down and took out my pocket recorder, setting it down between us. "Please."

"Ha," Mikoyan sat opposite me and composed himself. "Lightning was meant to be our answer to the American's bombs. It was a network of manned satellites, orbiting out of our enemies' reach, each one armed with thermonuclear weapons. Even if the capitalists wiped out our country, we could still retaliate."

He leaned forward, his eyes glittering with the memories. "I was selected to be the commander of the first of the Lightning stations. There were three of us, launched from the complex at Semipalatinsk."

"I thought launches took place at Baikonur?"

"Not this one. There were two rockets - one for us, one for the Lightning. We launched simultaneously, riding twin pillars of flame towards the heavens. Everything was perfect, then ... ." Mikoyan's voice faltered. He took a drink of tea and grimaced. "Do you like vodka?" I nodded. "Good," Mikoyan said. "We shall have vodka. It is good to drink at times like this."

He hauled himself out of his seat, and retrieved a bottle and two greasy tumblers from one of the shelves. This done, he poured out two generous measures of vodka - one for me and one for him - before sitting down. Mikoyan raised his glass and contemplated it for a moment before taking a gulp of the powerful spirit.

"Something happened. I do not know what. There was a flash. I remember thinking that one of the bombs in the Lightning had detonated. The air in our capsule became like a furnace, stinking of hot metal. Then we were tumbling back towards Earth. I tried to unlock the controls, but there was no time. Fortunately the automatics were still functioning - good Russian technology! - and our parachutes deployed.

"We landed somewhere in the taiga. Badly. The impact broke Vassily's arm. I had concussion. It took two days for the rescue team to reach us. But they were not friendly. They treated us like spies, interrogated us. It was as if they did not know who we were.

"We told them our story, insisting on the details. How could we have faked our landing? They had us on radar on the way down, yes? But they told us that there had been no launches. I told them to speak to the Chief Designer, but even he denied us."

"What happened next?" I asked.

"What happens to all official embarrassments in Russia. They told us we did not exist - that we never had! They told us our talk of Lightning was treason! They told us we were mad! And then they put us into the psychiatric hospitals."

I knew what that meant in the Cold War Soviet Union. The psychiatric hospitals had not been places of treatment; rather, they were places where dissidents and politically inconvenient were hidden and drugged into oblivion. I tried to sound sympathetic. "When did they let you out?"

Mikoyan shrugged. "I do not know. All I can tell you is that one day an official came to me, talking about 'openness' and 'restructuring'. He apologised to me for the way the Soviet state had treated me. I was released with an apology, with new papers and given this place." He gestured at the walls of the flat. "And that was it."

"And the others?"

Mikoyan shrugged and took another gulp of vodka. "Gone. No records."

There was one question I had to ask. "How do you know this wasn't all just a delusion, like the authorities said?"

The old man's face darkened. He was silent for a moment. Then he stood up. "Come."

I followed him into the bedroom. It was filled by an unmade bed that smelled of old flesh. On a small table beside it was a balsa wood box. Mikoyan went to the box, opened it and pulled something out. "Here. Look."

In his hand was a circular patch of fabric, about 10cm across. The finely-woven threads showed the shield of the Soviet Rocket Corps, orbited by what looked like an example of vintage Soviet space hardware. A pair of lightning bolts framed these images, and the letters 'МОЛНИЯ' were stitched in below them. Molniya. Lightning.

"This is my evidence," Mikoyan said quietly. "I kept this with me, to remind me. When they sent me to the hospital, I begged to keep it. One of the orderlies was sympathetic and looked the other way. I never let it go. It reminded me of who I was, not who they wanted me to be."

I stayed with Andreij Mikoyan for another hour, asking him about his experiences. He told me everything he could, but, in the end, it was no use to me. I knew there would be no evidence to support his claims of being a cosmonaut, no record of any secret project to put nuclear weapons into space. It all may as well have been a fantasy concocted in a drug-induced stupor. As I left, I shook hands with Mikoyan. He pulled me into a close hug - his breath reeked of cheap vodka, halitosis and despair - then held me by my arms.

"You believe me?" he asked hopefully.

"I don't know."

Mikoyan laughed bitterly and shook me. "You are at least honest. Good. Be sceptical. I do not blame you. It will stand you in good stead. Some days, I do not believe it myself."

He unlocked the door and let me out, back into the cabbage-flavoured corridor. Then I went down the staircase and headed back to Moscow.