"I come in peace."

Those were among Liberal leader Philippe Couillard's opening words as he arrived at TVA's debate studio last night. He'd eat those words just over an hour later.

"There's the matter of some $400,000 in party financing, missing from the Liberal books."

"What was your business plan [with Arthur Porter, who was arrested in Panama]?"

Quebec Votes 2014 Party Leaders

François Legault, Philippe Couillard, Pauline Marois and Françoise David faced off for the last time on Thursday, before voters go to the polls on April 7. (Jason Boychuk/CBC)

"Do you find it morally acceptable ... that, for years, you put huge sums of money in a tax haven?"

Three different questions from three different leaders, and with every line of defence Couillard trotted out:

"That money doesn't exist."

"I find it deplorable you'd find me guilty by association."

"No Canadian working abroad, with non-resident status, has to pay income tax here."

... in came another salvo. Another interruption, another accusation, another urgent defence, with nothing less than his credibility on the line every single time.

Such was Couillard's curse: of not having a governing record to trumpet, yet being squarely in the cross-hairs of each other party leader.

They're united by the common knowledge that Couillard has been building momentum in the polls, and that he represents their greatest threat.

Couillard's challenge was to rise above — to demonstrate to voters he is, indeed, leadership material. When challenged, though, he continually fell short. His demeanour of calm became curt; his patience replaced with exasperation.

Tanné, as we say in Quebec, like a boxer who'd taken one too many on the lip.

Legault on the attack, Marois lashes out

Perhaps because he has very little left to lose, Coalition Avenir Québec leader François Legault (currently running a distant third in the polls) was unrelenting.

Early in the debate, he launched into a tirade about how successive Liberal and PQ governments have increasingly indebted Quebecers by billions of dollars a year.

Then he left both party leaders to scrap it out over who, between them, managed matters worse.

"It's like a contest [between you two]."

His ferocity on the debate floor was tangible enough to visibly rattle Couillard. At one point, Couillard resorted to lecturing Legault: "I don't need to denigrate your plan to talk about my own."

But some of the most fervent exchanges were between Legault and Pauline Marois.

Grilling Marois on the PQ's poor full-time job creation numbers:

Legault: "You have not created a single full-time job while you've been in government."

Marois: "I have an exceptional team..."

Legault: "Not a single..."

Marois: "I've brought in major investments from..."

Legault: "...full-time..."

Marois: "I'm certain we're going to be able to..."

Legault: "NOT A SINGLE..."

And it went on.

Marois's problem is that as the leader of the governing (and struggling) Parti Québécois, she has everything to lose, and has become increasingly desperate to reverse her party's misfortunes.

Her attempt to dominate conversations — whether she was directly involved in them or not — even had the moderator, Pierre Bruneau, threatening to cut off her mic.

On headscarves and referendums

Some of the most impassioned moments came with discussions of the so-called Secular Charter, and the possibility of a referendum.

Failing to get the yes or no answer he'd sought in the last debate, Legault once again grilled Couillard: "Should a police officer be allowed to wear a religious symbol?"

Couillard: "Mr. Legault, you're a businessman. You've said yourself, a businessman deals with problems that actually exist. There's not a single police officer in Quebec who wears a religious symbol."

Legault: "You're skating ... You're not capable of defending Quebec values."

Couillard: "You're being borderline insulting."

That Couillard actually had a logical answer to Legault's question didn't matter. That he actually agrees with the fundamental notion of having some kind of established guideline on the issue of reasonable accommodation: irrelevant.

Legault's plan of attack was to sling accusatory soundbites, one after the other. In that, he succeeded on two fronts: he stayed in the spotlight, and he backed Couillard into a corner.

But Couillard had his moments. His strongest: brandishing the spectre of a PQ-led referendum. It's a tried-and-tested tactic, to the point where his entire campaign may hinge on it.

"I've said it a hundred times," Marois began, "and I'm going to say it again looking you right in the eye."

You could almost see Couillard follow the bouncing ball at the bottom of the screen — he knew every word, syllable-by-syllable, that was to come.

"There will be no referendum," said Marois, as Couillard's head cocked back, waiting for the familiar refrain: "... until Quebecers are ready for one."

His reply: "What I'm denouncing is not that you're sovereignist, but rather that you don't have the honesty to tell people you're going to trap them into a referendum the moment you arrive in government."

It was a counter-punch to which Marois had no real reply, and to date, no amount of "how much clearer can I be?" has sufficed.

Day after day, Couillard has hammered home the notion that Marois is on a one-track warpath to an independent Quebec, and yesterday's debate shows that this will continue to be his trump card.

English on the factory floor

If one of Couillard's greatest strengths is his "the-referendum-is-coming" message track, his greatest weakness-to-come may be on protecting the French language.

In a protracted debate with Québec Solidaire leader Françoise David, he defended bilingualism on the factory floor, saying workers need to be able to speak with visiting international clients in English.

"Bilingualism isn't a threat," he continued, "knowledge of English is indispensable."

It provided an opening for CAQ leader Legault and PQ leader Marois to actually agree on something: how abhorrent it was that Couillard saw no need to protect the French language.

"I'm flabbergasted to hear Mr. Couillard tell us that there is no problem with the French language in Quebec," said Marois.

Couillard tried to interject that he never, in fact, suggested that. But Marois continued: "I find it catastrophic to think he could one day lead Quebec and defend our language. He doesn't even understand the issues facing us in our factories, businesses and neighbourhoods."

Legault responded: "I agree with you Madame Marois, it's incredible to hear Mr. Couillard tonight, who doesn't want to defend the French language, who denies a problem in Montreal even exists; we've never seen that from a leader of the Liberal party."

"Never," exclaimed Marois.

Couillard's attempt to set the record straight fell flat, and it is that headline we may very well see around the province in the days to come.

That works very much to the PQ's advantage.

On social media, the reaction was immediate, visceral and passionate. From pundits, too, there's already been an explosive reaction.

To be fair, there are also those who were inspired by Couillard's staunch defence of bilingualism — but even so, the issue is a polarizing one.

There are frequent skirmishes on that territory — the battlefield of extremes — and it's where the Parti Québécois feels most at home.