By Jenny Cuffe
BBC Radio 4
Tens of thousands of African migrants set out for Europe every year. Many pay human smugglers to get them across the Sahara or Mediterranean but die on the way.
The truck was loaded with drums of water and sacks of food, with room on top for about 15 passengers - but there were 30 or so young men waiting to climb on board.
Tuaregs have traversed the Sahara for hundreds of years
They were impatient to be gone, yet scared of the emptiness that lay ahead: the miles of featureless sand with no shelter from the relentless sun or the bitter night wind.
When I offered my business cards, saying I would like to hear from them if they reached their destination, they rushed forward like children clamouring for sweets.
Their smugglers, Tuaregs in turbans and long white robes, glared at us suspiciously.
That evening, in a desolate spot outside Agadez, I had no idea whether I would be able to trace individual journeys across the Sahara, putting names and histories to the statistics of migrants arriving in North Africa and Europe.
I knew where these men came from - countries like Ghana, Burkino Faso and Somalia - and that they were dreaming of a share of the riches they saw on television and advertising billboards, but I did not know some were about to die in the sand dunes.
A month after my trip to Niger, I received an e-mail from one of the men who had taken my card.
He was called Alfred Kofi and he wrote: "I nearly lost my life at Sahara desert. I starting this journey with my friends. We move together from Ghana, but as for now l am alone because two of them lost they life due - water problem. We met so many different strange things at midnight."
Alfred was in the desert town of Sebha in Libya, more than 1200 km (746 miles) from Agadez and 800 km (497 miles) from Tripoli on the Mediterranean coast.
We spoke regularly by phone over the next seven weeks, while I waited for the Libyan embassy to grant me a visa.
He sounded increasingly desperate, frightened that he would be arrested and sent to the nearby deportation camp, like other Africans he had met.
On one occasion he arranged for me to speak to detainees in the camp, who complained they were beaten and treated like animals.
Human Rights Watch had recently criticised Libya for its arbitrary use of detention and for denying detainees access to legal and medical assistance, but Libya's minister for European affairs, Abdul Ali al-Obeidi, dismisses the claim and says conditions for migrants are far worse in other countries.
Arriving in Tripoli, I saw Africans working on construction sites, restoring the old Italian facades and gardening in the park that runs along the seafront.
Ghanaians Mac and Martin described a dual existence, employed as security guards at foreign embassies, yet forced to lie low whenever the immigration police were rounding up "illegals".
In the late 1990s, Libyan leader Muammar Gaddafi welcomed sub-Saharans as part of his pan-African policy, but now Libyans accuse them of bringing crime and disease. Encouraged by European leaders, the government has decided to tighten its controls.
As a journalist I was assigned a government minder and knew that all my movements were likely to be watched.
I now faced the difficulty of reaching Alfred without alerting the authorities to his presence as an illegal migrant.
Inventing a pressing need to visit the town where Colonel Gaddafi had gone to school and burned with revolutionary fervour, I sought permission to visit Sebha.
With three days left before I was due to return to the UK, I eventually boarded a flight, with my minder in tow. Later, I left him having an afternoon nap while I went to find Alfred.
He was working as a call agent in a business centre, a room with three phone booths and a bare desk.
After locking the door, he told me what happened when the truck had moved off into the desert with its human cargo.
They had been travelling for 24 hours when seven robbers drove up in shiny jeeps and forced them at gunpoint to strip and lie face down in the sand.
Many of Alfred's group did not survive the Sahara crossing
As the smugglers sat chatting and eating, the robbers took all the money Alfred had hidden under his clothes, his shirt and half his food and water.
The migrants had carried enough for a four-day crossing but the truck lost its way in the desert before reaching a mountain where the driver abandoned his passengers, pointing them in the direction of Libya.
Alfred had travelled from his village in Ghana with a childhood friend.
His voice trembled as he described the moment when his friend lay in the sand begging him for water.
By this time, he had nothing to drink but his own urine.
"I had a little, but I couldn't give it to him because that is your life," he told me.
"We were all crazy. If it had been your mother or father, you couldn't give it".
His best friend, another companion from Ghana and four other men died of thirst and now he has nightmares in which his friend asks him to visit his parents and tell them what happened. Alfred tells me he is unable to give such painful news.
Handing out a phone number and e-mail address in Agadez seemed such an ordinary thing to do, for me, but Alfred had clung on to the card throughout his ordeal as if it were a life-line.
When he then e-mailed me, he was giving me the story I had set out to get, but he was also giving me more responsibility than I had bargained for.
Desperate Dreams will be broadcast on BBC World Service in three parts starting Sunday 13 January and ending Monday 4 February 2008. A shortened version of this programme was broadcast on BBC Radio 4 Tuesday 8 January at 2000 GMT.