The victim was warned that he would first feel feverish, then sweaty and dizzy, then he would vomit and die from a lethal virus, unless he paid €12,000 (£10,160) as his own ransom.
The Russian kidnappers who seized one of their compatriots on the Costa del Sol convinced him that they had injected him with an experimental virus developed by the KGB that would kill him in 24 hours. The hostage's only alternative was to hand over the cash, in return for the antidote "that only they possessed".
He was then freed, with the Russians expecting him to come rushing back, cash in hand. But, suspecting he was being taken for a ride, the terrified victim, who had been abducted in the popular Spanish coastal resort of Estepona, took a chance and sought refuge in the town's police station.
Estepona, a popular destination for British residents and holidaymakers, lies in the heartland of Russian mafia operations on the Costa del Sol, which police say have multiplied in recent years. There is a specialised police unit to deal with them, based in Malaga just up the coast.
When officers from this elite Drug and Organised Crime Unit rounded up the kidnappers, aged 24 to 57, there was no need for the mythical antidote: the victim had recovered.
He told police his kidnappers seized him in broad daylight, covered him with a hood and held him for two days in a house where he was beaten, threatened, and subjected to electric shocks in an effort to extort money from him.
Finally, they pretended to inject him with a killer virus they said had been developed by the former Soviet secret police. They then freed him so that he could round up the ransom cash, having arranged a rendezvous at a café terrace in San Pedro de Alcantara, a few miles along the coast.
The police made careful preparations. Knowing they were facing burly, armed criminals, they mobilised plain clothes and special operations officers to ambush the kidnappers, who put up strong resistance, according to local press reports.
One of the men detained had a mobile phone hung round his neck containing photos of the torture to which they had subjected their victim. A woman was detained in possession of a shotgun.
It was the second Russian kidnapping in Estepona in two months. Mafia gangsters kidnapped the wife and daughter of a Russian businessman in March, demanding a €2m ransom. The women were freed within 24 hours.
The suspected leader of one of Russia's top mafia gangs, Gennadios Petrov, who has petroleum interests in Azerbaijan, was captured last year in his mansion in Calvi, a luxury resort in Mallorca, in a massive police operation that netted 20 suspects along the costas.