Six months later, Azeteng boarded a bus to Abeka Lapaz in the west of Accra, where he walked along the side of the nine-lane George W Bush Highway until he reached a nondescript two-storey building, home to CSIT Limited — purveyors of computer products and technical solutions, including secret cameras. He had already done some research into the various types of secret camera available. There was the button, the pen, the clock, the watch, and the glasses. At 200 cedis — about £30 — the glasses were the cheapest. They were capable of recording only low-resolution images and they worked poorly at night. Later, British police would have to examine the footage carefully as they pieced together Azeteng’s story. But as he looked at himself in the mirror that day, Azeteng was just pleased to see it would take a second, third, probably fourth glance to spot that anything was amiss. He bought them, and called them his secret spectacles. For five months, while he saved, Azeteng practised filming and hiding the memory cards in his mouth — a trick from a spy film. Then he sold his livestock — two sheep, six goats and 10 chickens — and set a date to leave. At this point, no-one knew about Azeteng’s wildly dangerous idea except for Azeteng. So he told his priest: he intended to get himself smuggled on the desert migrant route to Europe, using a secret camera in his glasses to document the crimes of the smugglers. The priest asked him if he had considered the dangers involved. Azeteng said he had. “I thought it was a service to the world, a service to restore human dignity,” the priest told me later. “I said I would offer Mass for him while he was away.” Next Azeteng told his father, who now lives in a stone house on a small plot outside Accra. He still has the bearing of a policeman, though slightly faded by retirement, and he still rears livestock, which roamed the plot while we sat inside, away from the fierce afternoon sun. “I was mad, mad because I couldn’t understand why he wants to take that risk,” he said. “Sincerely, I did not give him my blessing. Then he called to say that he had taken off, and I said, well, that is his choice. God be with you.”

Azeteng had packed a few items of clothing and made a razor cut in the lining of his rucksack to hide his cash. Then he walked to Kinbu Junction, a teeming transport hub in downtown Accra, and asked three young men if they were going north. They said yes, they were headed for Europe — across the water to Italy or Spain. They gave Azeteng the number for a smuggler named Sulemana. Sulemana told Azeteng to board an ordinary bus to Bamako, the capital of Mali, where they would meet. Azeteng had taught himself to record phone conversations, and he recorded his conversation with Sulemana and took detailed notes. The bus pulled out of Kinbu Junction. Azeteng wrote in his diary: “Saturday, April 15, 2017 — depart for Mali. 9.15am GMT.” The bus crossed into Burkina Faso and then Mali, via checkpoints where small amounts of money were extorted by the police. After three days they reached Bamako. Sulemana arranged a fake travel vaccination certificate for Azeteng and demanded 45,000 CFA — £60 — for the next stage of his trip up to Gao, where Azeteng would meet Sulemana’s boss, Moussa Sangare. At the bus station, somewhere close to a thousand migrants milled around in the heat. Azeteng took out his diary. “Every five minutes a bus will set off with African migrants and those trafficked,” he wrote. “It is more like a busy international airport.” He wrote down a detailed description of Sulemana and the smuggler's phone number, then he boarded the bus. After a few hours on the road, Sulemana called him. “If anyone asks you where you are going, tell them you are going to visit your relative,” he said. “Do not tell them you are going to Europe through the desert.” Sulemana told Azeteng to prepare for his cash to run out, and to have to call home to ask for more along the way. “It is like I told you,” he said. “The road is all about money.” After two days, the bus arrived in Gao — the gateway to the Sahara.

Gao is a city of hot dust-red streets and mud-brick houses, where migrants flow hourly into the city’s main bus station. Many, like Azeteng, already have a phone number of one of the city’s connection men, who house migrants for a few days before selling them on to be taken across the desert. Anyone without a name and number is a target for coaxers — young men who board the buses outside the city to hustle migrants for their smuggling bosses. Azeteng knew to ask for Moussa Sangare and soon he was in Sangare’s ghetto house. He moved through the house discreetly taking photographs with his flip phone and writing down what he saw. Moussa Sangare appeared to take money from Malian security officers. He paid the connection men and boys who worked for him. When he had a certain number of migrants, he transferred them to the Tuaregs for the drive across the desert. Everything in his house — food, drinking water, a bath — cost money. After three nights in Gao, Azeteng was called up to pay the $400 fee to continue north. Here was the final moment of safety before the dangers of the open desert. Ahead of the migrants lay at least six days in the Sahara, but in all likelihood many more. EU-funded patrols were targeting the smugglers, pushing them to take longer, more remote routes. Trucks, laden with human cargo, became stuck. Migrants were dumped miles from cities and forced to walk, or waylaid for weeks as they worked to pay their way on. Out on the desert, the lines between smugglers and traffickers, victims and perpetrators, would blur. Sand dunes would shift in the wind, leading even seasoned drivers astray. But as Azeteng lined up to leave Gao, few seemed to dwell on the dangers ahead. The crowd buzzed at the imminent departure. In front of them were Toyota Hilux pick-up trucks which would ferry them to a warehouse to board larger, ageing transport trucks. Azeteng was packed into a truck with about 75 others — all men save for two Nigerian women, who sat up front with the driver. Azeteng sat on the floor at the back of the second truck, his knees close to his chest, filming with his phone. Somebody switched on a small bluetooth speaker and the migrants sang and danced to pop music. Different languages and dialects rang out over the din — French, Bambara, Mandingo, Twi. As the convoy hit the open desert, excitement rippled through the truck. But the migrants were headed into northern Mali, a lawless black spot bereft of government forces, humanitarian agencies and journalists; controlled by militias and beset by jihadists. Azeteng sat quietly, a knot tightening in his stomach.