Unaoil's early approaches to Leighton Offshore in 2010 sounded almost legitimate.
"We are preparing an onshore pipeline installation package to send to you for your review," Unaoil's balding point-man Peter Willimont emailed to Leighton Offshore managing director Russell Waugh on   April 8 of that year.
It was seven years since the Coalition of the Willing's invasion and the overthrow of Saddam Hussein, and the country had established a government with American backing.
Unaoil knew - everybody in the world's richest industry knew - the cash would soon be gushing along fat, industrial-grade pipelines to those bold enough to be in the game. 
Leighton Offshore had its eye on pipeline construction jobs worth up to $2 billion. But it was also clear to all that winning contracts in a country like Iraq is not straightforward. So Willimont was proffering an inside track. The prize for both parties was huge. If Leighton Offshore won, Unaoil envisaged extracting tens of millions of dollars from the Australian company in commissions, enough to pay off Unaoil's corrupt officials within the Iraq government's South Oil Company and the oil ministry in Baghdad. This in turn would ensure Leighton Offshore, a subsidiary of Leighton Holdings, won the lucrative contracts.
Unaoil's chairman, Ata Ahsani, denies all this: "In all honestly we were not involved in any corrupt activity," he told Fairfax Media and The Huffington Post. "We were not involved in doing any marketing or any lobbying for Leighton."
But his denial is belied by thousands of emails, both to Leighton Offshore and within Unaoil. They show the Monaco-based firm was involved intensively and corruptly. A Jordan-based middleman known as the Doctor would be paid more than $20 million in return for access to the highest levels of the Iraqi government, right up to the deputy prime minister. Ultimately, Unaoil and its agent would pay at least five senior servants of the Iraqi people: some would go on retainers, some would be paid big, one-off bribes.
The Aussies themselves were no innocents. Leighton Offshore chief Russell Waugh and, to a lesser extent, his successor Peter Cox not only knew about the corruption but, at times, were active participants.
The strategy was a magnificent success. In 2010 and 2011, Leighton Offshore won work from the Iraqi government worth about $2 billion.
Some of this, the Australian Federal Police already know. They have been exhaustively investigating allegations Leighton Offshore paid bribes, but have so far not pressed any charges. Of course, until now, police have not had access to the explosive evidence detailed in Unaoil's emails.
WAKE UP AND SMELL
THE COFFEE
Driving Unaoil's Iraq push were the company's founder and family patriarch, Ata Ahsani; his son, Cyrus and their smooth, Iraqi-British employee, Basil Al Jarah, aka "the Captain". A former oil vessel commander, Al Jarah had a colourful turn of phrase and an uncanny ability to reach into the upper echelons of the Iraqi establishment.
In Leighton Offshore, the Captain liked what he saw. They "have a plan to win and are hungry and can do the job", he wrote to his bosses in   May 2010. The two companies soon signed a memorandum of understanding.
Al Jarah had good reason for confidence. Among Unaoil's best assets in Iraq was Oday al-Quraishi, the top project director in the South Oil Company who was in charge of running the first two phases of the tender.
Unaoil code-named him "Ivan", and had him literally in their pockets. Since   April the previous year, they had been paying him a monthly retainer of $US6000 - "$5k for him, and $1k he needs for presents to people within".
Also in their pockets was a man they called "Lighthouse", Ivan's boss, the director general of the South Oil Company. His real name was Dhia Jaffar al-Mousawi, and Unaoil had been systematically corrupting him since as early as 2008.
In Unaoil's emails with Waugh, Cox and others, the language used was polite, almost courtly. (Waugh could not be contacted for comment, and Cox did not respond to questions put by Fairfax Media and The Huffington Post.) Behind the scenes, the language, particularly from Al Jarah, was earthier.
Iraq's oil industry and the South Oil Company were "a nest of vipers". Waugh, with his initial belief that he alone could navigate this snakepit, was a "dozy sod", "not that smart", "an idiot", and "so naive it's beyond belief".
Al Jarah was convinced that Unaoil's contacts in Iraq were better than any of the Iraqi middlemen already recruited by Leighton Offshore's executives: "[Waugh] better wake up and smell the coffee," he wrote in an internal email. "He will be torn to pieces ... Without us he hasn't a snowball's chance in hell."
THE DEAL
The three-stage, $2 billion-plus southern oil fields projects were among the biggest and most important in Iraq's oil industry reconstruction. New pipelines connecting an offshore terminal could help triple Iraq's oil-pumping capacity and boost the country's economy.
Leighton Offshore, with Unaoil as its consultant, wanted a piece of all three stages, tendered over a hectic 13 month period in 2010 and 2011. In hundreds of emails dedicated to winning stage one, we see Unaoil scrambling to buy Leighton Offshore a result.
Bribery in Unaoil's emails goes by many names. It is "days available", "days off", "man hours", "holiday arrangements", even "train times". But in the early days of 2010, with the scale of the Iraq project in mind, Unaoil began to worry that its existing corrupt network may not provide enough certainty. So Al Jarah approached a well-connected Jordanian middleman, Dr Ahmed al-Jibouri.
In internal Unaoil correspondence, al-Jibouri was assigned the code names "The Doctor", and "Armada". The doctor had friends in the highest places, including the Deputy Minister for Oil, Abdul-Kareem Luaibi, code-named "M", and the Oil Minister himself, Dr Hussein al-Shahristani, who was code-named "Teacher".
Al-Shahristani was later appointed deputy prime minister of Iraq and is now education minister. He denies to Fairfax Media any wrongdoing, and says he does not even know al-Jibouri.
Unaoil's emails reveal that access at this level does not come cheap. The agreement with al-Jibouri initially involved $4.5 million for his "support service consultancy". This figure would soon grow. And grow. It's clear that Unaoil did not expect he would keep it all: "he is a tool," Al Jarah wrote. Much of the money was ultimately destined for those in the ministry who were, he said, "right assholes, and greedy".
As the tender for the first tranche of the project inched along, Unaoil's corrupt network greased wheels at every level. "Ivan," "Lighthouse", "Doctor", "Teacher" and "M" between them sidetracked a request from oil ministry officials that Leighton Offshore discount its bid price by $50 million. They obtained and passed on privileged information.
The contact was intense, and,
at times personal. In the first week in   September 2010, Oday "Ivan" al-Quraishi was in London for meetings.
"Ivan has requested if we can make him an appointment with stomach doctor in London," Al Jarah wrote. "He wants his colon checked out."
VICTORY IS CLOSE
As the prize drew nearer for Leighton Offshore, other corrupt officials were starting to approach the Australian company directly, grubby hands out, claiming they could influence the result.
"We are aware that several approaches are being made by everyone and his mother to R [Russell Waugh]," Al Jarah wrote. "Please tell R to hold his nerve ... If he has any cash to spare he should give it to us as we are driving these proceedings at the Ministry now."
On the morning of   September 23, 2010, $733 million worth of good news landed in Unaoil's inboxes. It's a small piece of a big puzzle, but illustrates what extraordinary access Unaoil had: "Please note, Minister of Oil [al-Shahristani] has signed award letter to Leightons half an hour ago," Al Jarah announced. "Only one copy of the letter exists and it's in the Minister's briefcase. But hope to get a copy in a couple of days."
An internal Leighton Holdings document later revealed that by late 2010, it had promised $87 million to Unaoil. Perhaps half of this or more was used to pay bribes. In the real world, the payment increased the cost of a landmark project for the poverty-stricken Iraqi people to benefit a group of Monaco multimillionaires, some Iraqi public servants and politicians, and the shareholders of an Australian listed company.
Around this time, "Ivan" - the senior Iraqi oil company official Oday al-Quraishi - visited London. Unaoil's Al Jarah observed of him: "He is getting rich. He wants me to accompany him this morning to see a flat in Chelsea to buy".
THE NEW PROJECTS
Victory did not dull Leighton Offshore's appetite. Unaoil and Leighton Offshore bribed their way to a $66 million extension to the first tranche of the project, and also set their sights on the $600 million third tranche, funded by a soft loan from the Japanese aid agency, JICA.
For this contract, though, Unaoil wanted to avoid the expensive and risky tender process entirely. They told their powerful Iraqi government friends that it should simply be awarded to Leighton Offshore as a "variation order" to the first contract.
Al Jarah acknowledged obtaining such a result would be a "mountain ... to climb", but he laid out a plan. Step one was to replace the Iraqi government project manager with Unaoil's hand-picked candidate. A short time later, the project manager was replaced - the new decision maker was an old friend of Al Jarah's.
Al-Jibouri, "the Doctor," who had been so instrumental in delivering Leighton Offshore the first contract, also smelled a big payday for the third tranche, demanding $20 million from Unaoil.
"Too much for engineering work in Iraq," complained Unaoil managing director Cyrus Ahsani, in code.
Back in the Australian company's Sydney headquarters, concerns were also being raised. An internal Leighton Holdings memo in   November 2010, revealed that Unaoil was asking for $50 million to $60 million more for "onshore work" on the JICA bid - essentially the operation of a workers' camp and other subcontract tasks. The actual value of this work was less than half the sum.
"It is too much money and a clear lack of value for money and we should not do it," the Leighton Offshore's memo said, noting that the deal involved kickbacks.
Three weeks later, Unaoil and Leighton Offshore signed an agreement that included a $25 million "marketing" fee for Unaoil. Unaoil in turn agreed to pay $16 million to "the Doctor". It was the biggest single "holiday", or bribe payment, Unaoil had ever granted.
But as these huge numbers were being agreed upon, Leighton Offshore's managers were buying insurance. Russell Waugh was dealing personally with "Ivan" without using Unaoil as an intermediary. A 2011 Unaoil email quotes the Iraqi official boasting that he had "made his own holiday arrangement" with Leighton Offshore and had "no need for a travel agent" in the form of Unaoil.
The attempts to avoid a tender did not go well. The Japanese funders would not be swayed so, on   April 18, 2011, the bidding began. Once again, Unaoil went to work to corrupt it.
The new head of the bid committee, Al Jarah's old friend, was given the code name "Walker." He started feeding confidential information back to Unaoil. He was directed to "knock out" Leighton Offshore's competitors and was given a "holiday" in return.
But as work continued, Unaoil's well-heeled principals grew more worried that their Australian client would double-cross them. Waugh had gone by this point, replaced with a relatively unknown quantity, the new Leighton Offshore boss, Peter Cox. They code-named him "Fox", and found him as difficult to deal with.
Cox had agreed to pay Unaoil tens of millions of dollars in additional fees, but he was slow to sign and return a payment contract. He was hard to get on the phone, and he was increasingly dealing directly with Iraqi officials, sidelining Unaoil.
"Please get Fox to work with us," Al Jarah wrote in one email to his bosses at Unaoil, "it's crazy he is going at a tangent with [corrupt official] Ivan at this crucial time."
THE DOUBLE-CROSS
In   October 2011, Leighton Offshore won the JICA-led tranche of the South Oil field project. At $600 million, it was only slightly less lucrative than the first tranche. The Australian company had, through hook and crook, won two out of three tenders. Then the Australians reneged on their agreement to pay Unaoil.
What happened next is a breathtaking piece of effrontery. The Monaco bribe factory went to the British High Court to enforce its right to receive under-the-table payments relating to a corrupted contract. Even more breathtaking is that, in part, it won.
Everybody in court denied corruption had been involved, and the judge accepted their assurances. He awarded the Monaco company more than $6 million. It's still the only time that this saga has seen the inside of a courtroom. The criminal courts, where these issues should ultimately be judged, have been untroubled by the case.
A month after the JICA contract was awarded to Leighton Offshore, in   November 2011, the Australian Federal Police were handed an internal Leighton Holdings document alleging serious corruption. They have not yet laid charges.
In 2015, anxious to escape the brand damage from corruption allegations, Leighton Holdings' new Spanish owners changed the company's name to CIMIC. Some of Leighton Offshore's former executives might find that, with the email cache now public and known to police, their own reputations are more difficult to mend.
And the next case might be heard in the criminal courts.
KEY PLAYERS
RUSSELL WAUGH
Former Leighton Off shore boss, attempted to circumvent middleman and deal direct with corrupt officials.
PETER COX
Waugh's successor. Signed an agreement to pay Unaoil millions of dollars, but did not stump up.
PETER WILLIMONT
Senior Unaoil executive, helped sway Leightons Off shore to hire Unaoil. Involved in corrupt dealings in many countries
BASIL AL JARAH
Unaoil's Iraq country manager. Possessed an incredible network of contacts who influence the highest levels of Iraq's government.
HUSSAIN AL-SHAHRISTANI
Former Iraqi deputy prime minister, received bribes and helped Leightons Off shore win more than a billion dollars worth of work.
THE EMAIL TRAIL
From: Basil Al Jarah To: Peter Willimont; Ata Ahsani; Cyrus Ahsani Date:   May 30, 2010
" 1) Ivan talked with R, relayed the agreed message about knives coming out..
R was concerned about getting enough help at the Ministry. He always wants assurance that we carry enough clout. It was confirmed to R that we the right people,
2) Following on from various discussions this morning with AA, I discussed with Ivan for ways to increase L's price through variation orders and requests by the client for increased scope... Ivan stated that R has left no room in his off er for such plan of action.. he has already said yes to everything and no caveats to fall back on.. dozy sod...Basil"
From: Basil Al Jarah To: Ata Ahsanii Date:   February 4, 2011
"Please note the ministry wants big discount on Leighton's price. Also it's not a sure thing they will approve it as SOC and Leighton expect...
You must make R understand decision is not in the hands of Ivan no matter what story he is telling them. His role is to send it to the Ministry, and now must have approval from Minister, Ivan is no longer in decision process, and getting more then (sic) his worth. Sometimes R is so naive it's beyond belief..."
From: Basil Al Jarah To: Ata Ahsani Date:   August 25, 2010
"We are aware that several approached are being made by everyone and his mother to R that they can ensure award in one week. These people are jumping on the band wagon taking advantage of the hard work we have put in place.. Please tell R to hold his nerve and not relent. If he has any cash to spare he should give it to us as we are driving these proceedings at the Ministry now."