A forensic investigation that has crossed the Atlantic

Secret deals, secret meetings and a cunning plan to pocket millions of dollars allegedly link the NatWest Three to the once mighty Enron Corporation.

It was in 2000 that, according to charges filed against the three in a federal court in Houston, that the trio hit upon a plan to enrich themselves with the help of a handful of officials at Enron.

At the time the three men worked for Greenwich NatWest (GNW), a finance division of the high street giant, that had offices in London and Connecticut. Facing a ultimately successful takeover bid from its rival Royal Bank of Scotland, NatWest was trying to raise funds and had decided to put GNW up for sale.

The future of the NatWest Three - David Bermingham, Giles Darby and Gary Mulgrew - was allegedly uncertain.

It is at that point in the twisting allegations that things stop being simple. It is alleged that, in February 2002, the three travelled to Houston to meet Andrew Fastow, who was Enron's chief financial officer.

Greatly simplified, their alleged suggestion to Mr Fastow and his colleague Michael Kopper, was that the three men would suggest to NatWest that it sell off its stake in a Cayman Islands-based holding to a partnership created by Fastow and Kopper, in which the trio also had a stake.

They would tell NatWest to sell its stake for $1m (£550,000) even though they realised it was worth a lot more. At the same time, they plotted that Mr Fastow would arrange for Enron to plough $30m into the holding.

According to documents obtained by prosecutors, and reported by the Financial Times, before they left for the Houston meeting, the three men planned how to persuade Mr Fastow to take part in their scheme. "We should be able to appeal to his greed," Mr Bermingham allegedly e-mailed Mr Mulgrew.

Prosecutors allege that, once the transaction was completed, the three men exercised their option to buy the partnership established by themselves, Mr Fastow and Mr Kopper for just $250,000.

The alleged result was that the three men received a sum of $7.3m while Mr Fastow and Mr Kopper were left to divide about $20m of the money invested by Enron.

All the while that the alleged scheme was taking place, Enron, the once glittering jewel of the US corporate world, was little more than a year from exploding.

Indeed, it was in October 2001 that it was revealed that billions of dollars the company claimed to have simply did not exist. Huge financial black holes had been covered by corrupt accounting and dubious "partnerships" that were established to hide the losses.

A criminal investigation was launched and among those charged, the NatWest Three were accused of seven counts of wire fraud. They deny the charges.