Arlene Foster made fatal misjudgments over botched RHI scheme
Six months ago, few people in Northern Ireland had heard of the Renewable Heat Incentive, a dull sounding government scheme aimed at encouraging businesses to switch from fossil fuels.
Now everyone knows about RHI.
This scheme has not only precipitated the collapse of the power-sharing executive, it has also put the devolved institutions in doubt, triggered a snap election and undermined public confidence in our system of government from ministers down.
Specifically, RHI has dealt a damaging blow to the reputation of the DUP and its leader Arlene Foster, who - crucially - was the minister in charge of this scheme at the time of its inception.
Time and time again we see leading politicians falling into the same trap. It is not the original problem that proves fatal but how the issue is handled.
Alarm bells first began to ring in relation to RHI in July last year when the audit office highlighted widespread abuse of the scheme.
In the autumn, Stormont's public accounts committee began to uncover disconcerting details in relation to the scale of the cost to the taxpayer and the lack of controls that had been imposed on the initiative.
At that stage politicians must have realised that a major scandal was brewing and the natural instinct of a party under pressure is to try to minimise or dismiss concerns.
Certainly, the first time Arlene Foster was questioned about this issue, in October 2016, she told this newspaper she was not accepting responsibility for the scheme's shortcomings, blaming her officials and even other MLAs for failing to scrutinise it properly.
In a phrase that came back to haunt her, she poured scorn on the suggestion that she got to see `every single jot and tittle' that went on in her department.
Unfortunately for Mrs Foster, the public does expect government ministers to know what is going on in their departments, to be across the details and in the most fundamental terms, make sure public money is being spent properly.
As the scandal grew and the drip feed of damaging revelations continued apace, it seemed everyone except the DUP understood that this was a serious matter.
Perhaps no one anticipated back in October/November that RHI would bring down the executive, but in the lead up to Christmas it was clear that the DUP's partners in government were running out of patience, their grassroots telling them enough was enough.
Martin McGuinness offered Arlene Foster a way out but rather than show a bit of humility she remained defiant and is now fighting an election not from a position of strength but as a wounded leader whose strategy is more about scaremongering and insults than optimism and positive vision.
The story of RHI is not yet over. Next week we go to the polls and then talks begin to restore our battered institutions.
It was just a green energy scheme but it has had tumultuous political consequences.