The pickup halted in Kidal, the far-flung Malian desert town that is home to members of the Grammy-winning band Tinariwen.
Seven AK47-toting militiamen got out and marched to the family home of a musician. He was not in, but the message given to his sister was chilling: "If you speak to him, tell him that if he ever shows his face in this town again, we'll cut off all the fingers he uses to play his guitar."
The gang took guitars, amplifiers, microphones and a drum kit from the house, doused them with petrol and set them ablaze.
In northern Mali, religious war has been declared on music.
When a rabble of different Islamist groups took control of the region in April, there were fears that its rich culture would suffer. But no one imagined that music would almost cease to exist - not in a country that has become globally renowned for its sound.
"Culture is our petrol," says Toumani Diabate, the Malian kora player who has collaborated with Damon Albarn and Bjork, among others. "Music is our mineral wealth. There isn't a single major music prize in the world today that hasn't been won by a Malian artist."
"Music regulates the life of every Malian," adds Cheick Tidiane Seck, a prolific musician and producer. "From the cradle to the grave. From ancient times right up to today. A Mali without music? No … I mean … give me another one!"
And yet that is the reality dawning on this once joy-filled land. International observers claim the leaders of the three armed Islamist groups that now control the northern cities of Timbuktu, Kidal and Gao are motivated by money and power rather than the dream of a caliphate in the Sahel. There are strong ties between these groups and major drug and arms smugglers.
But many of the mujahideen who have zoned in on the conflict from all over the Muslim world are fired by an unquestionable religious zeal. The same goes for Iyad Ag Ghaly, a Tuareg strongman and born-again Salafist who founded the Ansar Dine movement at the end of last year.
"He believes in what he's doing," says Manny Ansar, director of the Festival in the Desert, which has been taking place in and around Timbuktu and Kidal every January since 2001. "And that's what frightens me."
Back in the 1990s, Ghaly liked to hang out with musicians from Tinariwen. Now music has disappeared or gone underground in the territory under his control.
An official decree banning all Western music was issued on August 22 by a bearded Islamist spokesman in Gao. "We don't want the music of Satan. Koranic verses must take its place. Sharia demands it," the decree says.
The ban comes in the context of a horrifically literal application of sharia law in all aspects of daily life. Militiamen are cutting off the hands and feet of thieves and stoning adulterers. Smokers, alcohol-drinkers and women improperly dressed are whipped.
Remarkably, al-Qaeda in the Islamic Maghreb (AQIM) never targeted the Festival in the Desert or the thousands of Westerners who attended it. According to Ansar, some people put this down to the fact that his tribe, the Kel Ansar, is said to be descended directly from Mohammed.
Not all music events were so blessed. Returning from the Tamadacht festival near the eastern town of Anderamboukane in January 2009, a British tourist, Edwin Dyer, was kidnapped and sold to AQIM, who beheaded him four months later because the British government refused to pay a ransom. His death forced the Festival in the Desert to move within Timbuktu's city limits in 2010.
The festival took place under high alert this January after recent kidnappings and the murder of a German tourist by al-Qaeda. It was attended by Tinariwen, other Tuareg and Malian musicians and Bono. "I was impressed by Bono's courage and that of his team," Ansar says.
Despite the threat to the culture, all the musicians agree it remains at the core of their identity. "I'm a Muslim, but sharia isn't my thing," says Rokia Traore, one of Mali's biggest stars. "If I couldn't go up on stage any more, I would cease to exist. And without music, Mali will cease to exist."