Regrettably for M Paul N’Guesso, his office in the Nabemba Tower was on the ‘poor’ side, which faced west, and consequently he had no view of the river, or of the office buildings and hotels in Kinshasa that lined the water’s far banks.

Still, he kept powerful binoculars mounted on a tripod by the window, to scan Brazzaville’s Poto-Poto quarter in idle moments. N’Guesso found the traffic disagreements engrossing. The taxi drivers, motorcyclists and truck drivers bumped and grappled like ants from competing nests.

He would also point his binoculars down to the street below, to see who was trying to gain access to the Tower’s premises, and how successful the guards were at turning vehicles away. N’Guesso, whose name indicated a possible family link with the President (he remained obscure on this point) had discovered a pattern: when the windows of the car were untinted, and he could see its occupants clearly, the odds were good that they would have to return another time.

He was watching a Toyota SUV idling by the guard hut. He could see the driver’s smiling face over the shoulder of the guard and, in the seat behind the driver, a white man, also doing his best to look friendly. N’Guesso’s building was the tallest for thousands of miles in any direction. It was a natural attraction for people visiting the city.

To his surprise, N’Guesso realised that he had seen the white man through his binoculars before. Two days ago, he had tracked the man’s progress as he jogged through the Poto-Poto quarter. It was not hard to pick him out - he wore a bright red shirt and yellow shoes, and stuck to the busier streets. He ran without tentativeness: perhaps he had studied a map beforehand.

The white man had jogged north, deep into the quarter, then reversed course, heading back to the diplomatic neighbourhood on the other side of the Félix Éboué stadium, where the hotels were. N’Guesso lost him at the Basilique: it was as though the great, green, spiny church crouching at the heart of the city had opened and swallowed him like a crocodile. After several minutes waiting for the man to appear on the other side, N’Guesso went back to his desk.

Now this same man was attempting to access the Tower. N’Guesso couldn’t decide whether the smile on his face was trustworthy, so he supposed it wasn’t.