In the early 2000s, Yekaterinburg was in the grip of a major heroin problem. For Yevgeny Roizman, ‘Russia’s vigilante king’, the solution was simple: first, send in goons to beat up the smack dealers; second, round up the city’s addicts, chain them to radiators, and force them to go cold turkey. The policy, unsurprisingly, failed. For one, Russia’s fourth largest city has swapped its preferred kick: today, it’s spice that is mostly getting Yekaterinburg’s residents smashed. At the same time, the city still counts enough heroine users for their needle-sharing habits to have sparked an official HIV emergency.Still, none of this stopped Roizman — an art collector, champion rally driver and ex-convict — from being elected city mayor. This is a man who, as a teenager, wore a Star of David T-shirt on a walkabout around Russia to ‘troll anti-Semites’.

The world of drugs is full of such colourful characters, from well-meaning medics and murderous mafiosos to anti-corruption crusaders and cookie crackheads. Dopeworld is a free-rolling and frank depiction of the global narcotics scene, in which Niko Vorobyov makes it his job to introduce us to as many in this crazy cast as possible. For sheer variety, he does not disappoint. His quest takes him to 15 countries on five continents. On the way, we meet the ‘really chill’ family of the Mexican drug lord ‘El Chapo’; an off-duty cop with an opium habit in Tehran; and the brother of arch narco Pablo Escobar (‘now basically a tourist attraction’) in Colombia.

This is no sober, arms-length account, either. The author’s approach to research is — how best to put this? — ‘applied’. The trajectory is set early on, with a graphic description of an ayahuasca ritual deep in the Peruvian jungle. One shot and Vorobyov is off with the fairies, battling with giant spiders ‘somewhere in Kermit Land’. He certainly seems to have a nose for where the action is. In Japan, for example, he finds himself bumping into a local drug lord during a public parade; the pair take a selfie. In Rio, meanwhile, he stumbles on a Baile funk rave in the heart of a slum, where he marvels at a teenage kid selling vials of cocaine ‘as if they were a selection of cheeses’.

Such apparent serendipity is, in fact, no coincidence. Vorobyov knows the drug game well. Much of his late teens and twenties were spent dealing narcotics and getting high. In 2013, the law eventually caught up with him. Arrested carrying ecstasy on the London Underground, he was sentenced to two and a half years in prison. In many ways, the book was born during those 913 days (or 1,314,873 minutes: he counted them) of incarceration. Being ‘more geek than gangster’, he took himself off to the prison library, where he read voraciously, including the drug convict’s text of choice, Howard Marks’s 1996 autobiography, Mr Nice.

An international drug-smuggler, Marks makes a powerful case for the legalisation of cannabis. It is an argument that Vorobyov endorses and one that, as he shows in the latter section of Dopeworld, is gaining ground in Europe and the US. But, political as it is in parts, the book is not a polemic. For that, it would have to be far more ordered and coherent than it is. Vorobyov is, both literally and literarily, all over the place. It is not that the book lacks opinions; it’s more that the opinions appear at random, like the addled pontifications of a bar-room drunk.

This is not necessarily a bad thing. After all, there is a long tradition of form following befuddlement in this field. Think Julio Cortázar’s Hopscotch or Malcolm Lowry’s Under the Volcano, both of which require a toke or two to make any real sense. That said, both authors exert a sublime control that Vorobyov sadly lacks.

To its credit, Dopeworld is nothing if not ambitious. Vorobyov states as much himself, describing it bombastically as ‘true crime, gonzo, social, historical memoir meets fucked up travel book’. That is a lot to cram in. If sometimes he drops the ball (the opium wars get a single page) or holds on too long (as with the chapters on prohibition and mob history), then perhaps it’s to be expected.

For all its structural problems, this remains an important book. Travel writing has taken a rarefied turn in recent years, with many writers seeming to spend as much time in the library as on the road. And when they do venture forth, it’s with an urbane and all-knowing air, as if they fully expected to find whatever they find.

Vorobyov does away with the thesaurus and brings the grit back to the genre. He tells it as it is, from inside the mix, with a voice unapologetically free of artifice or artistry. The gonzo slang may grate after a while, but it has the compelling benefit of ringing true. This Tinder date, for instance: ‘Although we never bumped uglies, we bonded over our love of doggo memes and cocaine.’ It’s not pretty, but it works.

Back in Yekaterinburg, during Vorobyov’s interview with Roizman, the mayor’s aide interrupts to explain that ex-policemen and ex-hooligans make the best enforcers. His reasoning? ‘The only ones who can do this are those with a “past”.’ The same is true of ex-drug dealers. Dopeworld may not be as finely varnished as your standard modern travel book. Nor will it have you reaching for the holiday brochure. But as a genuine insider’s account, it’s a fascinating read — hallucinatory warts and all.