WHERE'S James Bond - old or new - when you need him? A prominent Russian agent-turned-defector is poisoned in London. The finger points at the Russian president, because the victim was a defector who, we are told, had been investigating the recent murder of the Moscow human rights journalist and critic of Vladimir Putin, Anna Politkovskaya.
That a story adds up so neatly makes anyone who has dipped a toe into the swirl of Russian power-play suspicious from the start. M certainly would be.
For all the shock at the attempted murder of Alexander Litvinenko, we should remember that the received version of his story is being retailed largely at the behest of his main sponsor in Britain - Boris Berezhovsky, who has had his own tangled past in Russia and his own historical reasons for discrediting Mr Putin.
In our excitement at the new Russian wealth flooding the capital, we float over any suspicions, let alone disapproval, for roots of the oligarchs and the opaque agendas they bring with them.
Top PRs hawk their versions of the truth around: little wonder that London is known to moneyed Russians simply as the main "branch" of Moscow abroad.
They bring us the murk as well as the money. Mr Berezhovsky first offered himself as an interview to me among other Western journalists in Moscow when he fell out with Yevgeny Primakov, security chief in the Nineties who became Prime Minister. Later he made up with Mr Primakov - and fell out with Mr Putin. So it goes among the oligarchs: the stories and enemies change with the times.
That does not, of course, free Mr Putin of responsibility when a known "enemy" of the Russian state is targeted in London-But it does demand that we proceed rather carefully with the evidence.
Mr Berezhovsky is keen to link his own campaign for rehabilitation to the wider human-rights case against Mr Putin, and especially the Politkovskaya killing.
I do not "know", as others confidently claim, that the Kremlin ordered her murder. It had no intention of stopping it and voiced grudging regret, which is bad enough. The poisoning of the prowestern candidate for Ukraine's presidency in 2004 confirmed that Moscow was back in the murder game when its interests were threatened, and so it has remained.
Only last week, the Human Rights court in Strasbourg found the Russian state guilty of the "disappearance, murder and presumed deaths" of civilians in Chechenya between 2000 and 2002. Plenty of illicit bloodshed can be laid at Mr Putin's door that is rather better founded than any of the theories surrounding the attack on Mr Litvinenko.
The West struggles to find a response to this. Only Cherie Blair has commendably departed from the shy orthodoxy of the Foreign Office by voicing, during a recent visit to Russia, her concern at the treatment of charities such as Human Rights Watch and others which have been intimidated and forced to close.
All that notwithstanding, the Litvinenko case is a slippery one on which to pin an anti-Putin crusade. Litvinenko is a defector from the Russian secret service but he had been living here for some time and not thought to be especially high on the Kremlin's worry list.
If he was " investigating " Politkovskaya's murder (a tough task from London), on whose behalf? …