For the past three years, Brazil has been gripped by a scandal which started with a state-owned oil company and grew to encapsulate people at the very top of business – and even presidents.
On the face of it, it is a straightforward corruption scandal – albeit one involving millions of dollars in kickbacks and more than 80 politicians and members of the business elite.
But as the tentacles of the investigation dubbed Operation Car Wash fanned out, other scandals emerged.
It has led to some of those who have found themselves accused claiming they are the victims of political plots, designed to bar them from office.
But what is this scandal all about? And who is it said to involve?
What is Operation Car Wash?
Operation Car Wash began in March 2014 as an investigation into allegations that Brazil’s biggest construction firms overcharged state-oil company Petrobras for building contracts.
Investigators accused directors at the firm – named the world’s most ethical oil and gas company in 2008 – of skimming the extra money off the top as a bribe for awarding the contract.
Which is bad enough – but then the Workers’ Party found itself dragged into the corruption scandal amid allegations of having funnelled some of these funds to pay off politicians and buy their votes and help with political campaigns.
Among those accused in the scandal were dozens of politicians, and Luiz Inacio Lula da Silva – the country’s extremely popular former president, known affectionately as “Lula”.
Three years after the investigation began, Lula was found guilty of the first of five charges against him: that he had been given a beachfront apartment by engineering firm OAS in return for his help in winning contracts with Petrobras.
He has been sentenced to nine-and-a-half years in prison, although he will not be jailed until the outcome of an appeal.
But Lula, who denies all charges, says the investigation and trial were politically motivated to prevent him from running for president again in the next election.
Lula isn’t the only one to have held the presidency to face investigation right now: the two people who followed in his footsteps are facing corruption allegations of their own.
The attorney general has charged current President Michel Temer – the former vice-president who took office in August last year – with receiving money from the boss of giant meatpacking firm JBS, which itself is already implicated in a corruption scandal.
The charges have been delivered to a Supreme Court judge who must now decide if the case can be sent to the lower house of parliament, which will decide whether or not to lift his presidential immunity.
Mr Temer denies all charges.
And then there are the separate allegations which saw his predecessor Dilma Rousseff – who followed Lula into office after he had served two terms – impeached in August 2016.
What led to Rousseff being impeached?
Entirely separate to the Operation Car Wash allegations, Ms Rousseff – a close ally of Lula – found herself in trouble for allegedly moving funds between government budgets, which is illegal under Brazilian law.
She argued this was common practice among presidents, but her critics said she was trying to plug deficit holes in popular social programmes to boost her chances of being re-elected in 2014.
Ms Rousseff fought the allegations, arguing that her right-wing rivals had been trying to remove her from office ever since her re-election.
But she lost – and her vice-president, Mr Temer, of the centre-right PMDB party, was put in charge until January 2019, when the president to be elected in a vote next year will take office.
However, Ms Rousseff’s supporters do posit another theory when it comes to her fall from grace: they allege that the politician’s rivals wanted her gone because she would not shield them from the Car Wash probe.
Anything else you need to know?
Yes – there is one more scandal which involves those at the highest level: Odebrecht, which has also been caught in Operation Car Wash.
The Brazilian-based construction giant, which is Latin America’s largest construction conglomerate, has admitted bribing officials to secure contracts in Brazil and other countries in South America.
One of the companies it is said to have bribed? Petrobras.
In fact, its former CEO, Marcelo Odebrecht, who is serving a 19-year prison sentence for corruption, was found guilty of paying more than $30m (£21m) in bribes to Petrobras officials in exchange for contracts and influence.
He and 76 other Odebrecht officials are giving investigators information as part of a plea deal.
Mr Odebrecht may also yet bring down another president: he says part of the $48m he donated to both Ms Rousseff’s and Mr Temer’s campaigns in the 2014 Brazilian presidential election was illegal.
This is now under investigation by Brazil’s electoral court. If fraud is found, their campaigns could be annulled, which means that Mr Temer would be removed from office.
Both Mr Temer and Ms Rousseff deny all allegations of fraud.