Judge has unenviable task of deciding which whistleblower is to be believed
Two gardaí meet in a house in September 2016 and one gives information to the other.
One of them, former Garda press officer Supt Dave Taylor, says he was a key cog in a campaign to smear the other garda, Sgt Maurice McCabe - a vile plot he claims went to the top of the force.
Emotions run high. Sgt McCabe, long suspecting a smear campaign, is "furious" with Supt Taylor, who is in a "distressed or stressed" state.
The fury is put to one side, however, and an alliance of sorts is formed. Both men decide these matters need to be brought to the attention of the justice minister. They want the conspiracy exposed.
The minister receives two protected disclosures under whistleblower legislation later that month and within a fortnight announces a statutory investigation.
This was the genesis of the Disclosures Tribunal, the sprawling inquiry now in its 13th month. But it was not until this week, on the 59th and 60th days of hearings, that the public was reminded of the Taylor-McCabe axis.
On the first of two days in the witness box, Sgt McCabe gave evidence of what had been said at the meeting. You could hear a pin drop at Dublin Castle as he recalled Supt Taylor telling him: "I destroyed you." A clearly emotional Sgt McCabe gave his account of the conversation that followed.
Supt Taylor had told him former commissioner Martin Callinan composed text messages and instructed him to send these to journalists, senior gardaí and politicians.
The texts were said to have stated Sgt McCabe had been investigated for the sexual assault of a child.
While it is true that such a sexual assault investigation took place, the whistleblower was fully exonerated in 2007.
Sgt McCabe said Supt Taylor told him Mr Callinan's deputy, Nóirín O'Sullivan, had received these texts and would invariably issue a one-word response: "Perfect."
The tribunal heard Supt Taylor told him his three phones were seized under warrant and these would show all the text messages he got from Mr Callinan and sent on to Ms O'Sullivan.
Supt Taylor was said to have described Ms O'Sullivan as "the pusher", something Sgt McCabe interpreted as meaning she was pushing the agenda against him.
He said Supt Taylor told him there was an intelligence file on a special computer at Garda Headquarters, codenamed Oisín. An officer called Kieran was also monitoring Sgt McCabe's Pulse activity, Supt Taylor is alleged to have said.
"I could see that he was remorseful. I told him that I forgave him because I believed his apology to be genuine," Sgt McCabe said.
It was powerful testimony and Sgt McCabe was precise in his details. He said he was not saying he had evidence against the former commissioners, merely repeating what he was told.
Throughout the tribunal there have been many twists, turns and contradictions. So it was not entirely surprising to learn during Sgt McCabe's second day in the stand that Supt Taylor had a very different recollection of the conversation. Indeed, tribunal chairman Mr Justice Peter Charleton observed "a chasm" had opened between the two accounts.
He now has the unenviable task not only of deciding which account is the accurate one, but also of determining if the information in the preferred version is correct.
We have yet to hear evidence from Supt Taylor, but his counsel, Tara Burns SC, said her client disputed aspects of Sgt McCabe's testimony. For example, Supt Taylor's position is that texts sent to senior management, including Mr Callinan and Ms O'Sullivan, were not in relation to any sexual smear, but about developments or media broadcasts regarding Sgt McCabe.
She said Supt Taylor also disputes that he ever said Mr Callinan composed texts to be sent on to journalists, senior gardaí and TDs.
The reference to Ms O'Sullivan as "the pusher" was not in relation to spreading any sexual slur, but was a reference to her seeking to bring charges against Supt Taylor, the tribunal heard. Supt Taylor was suspended over an unrelated issue at the time but has since been reinstated.
The tribunal was also told Supt Taylor did not accept he named any officer who would have monitored Sgt McCabe's Pulse records and that the reference to an intelligence file being kept was only an assumption.
At one point Sgt McCabe observed: "It's his word against mine at this stage."
But as Sgt McCabe ended his evidence, Mr Justice Charleton indicated his conclusions would be based on evidence. He spoke of doing whatever was necessary to recover devices, establish if texts were sent and who was contacted. "That obviously is going to be a breach of certain people's privacy but it can't be helped," he said.
The judge said the tribunal had spent a great deal of time and money on this already.
But he is clearly not satisfied it has the full picture yet and asked Sgt McCabe if he was appealing to people who Supt Taylor was allegedly talking to co-operate.
Sgt McCabe said he was.