On an extraordinary night at Second City in Chicago, a fearless, vulnerable and determinedly transparent Margaret Trudeau took the stage to talk of affairs and mistakes, family and failures, rebellion and resistance, with her living children and their partners in the audience, sitting in ordinary seats along with regular Chicagoans (and a genial protective detail from the Royal Canadian Mounted Police), some wearing jeans, most drinking beer and wine, all staring up at their mother, wondering what she was about to say next.

This was a rare reunion of Canada’s most famous political family in, of all the weird places, the Second City UP Comedy Club at Piper’s Alley on Chicago’s North Side. Where, despite a press secretary accurately describing every aspect of this visit to the first weekend of Trudeau’s new show “Certain Woman of an Age” as personal, their hard-to-contain emotions were on inevitable public display.

The group included Justin Trudeau, the Prime Minister of Canada, currently embroiled in the kind of tough political campaign that is not usually helped by your mother opening up her box of photos and reminding everyone of an oft-scandalous past or by, say, showing an audience a picture of her own brain, part of her explanation of her determination to better understand her own mental illness and pass that awareness on to others.

Prime ministers seeking re-election are expected to engage with the struggles of those they represent. But they rarely are advised to advertise the personal emotions that flow from their own family histories. And they rarely hear their mothers say to an audience, as did Margaret Trudeau, “You may have heard whispers about me: ‘Margaret is crazy.’ It’s OK. You don’t have to whisper.”

Yet for much of a gripping, charming and intensely courageous night wherein Margaret Trudeau told her audience that her late-in-life “acceptance” of her bipolar diagnosis restored her will to live, the prime ministerial eyes were moist.

That was especially evident when his mother spoke of the devastating loss of Justin’s late brother, Michel Trudeau, who died in avalanche accident in 1998, a reminder that political success never alleviates personal pain.

Another of the children of Margaret and Pierre Trudeau, the writer and filmmaker Alexandre (whom his mother calls Sacha), raised his eyebrows at the beginning of the 90-minute performance as the screens on the stage filled with images of Margaret at Studio 54, at the White House with Jimmy and Rosalynn Carter and, famously, partying with the Rolling Stones. And although his face registered everything from laughter to sadness and palpable admiration to what looked like disbelief at his mum’s sheer chutzpah and survivorship, those eyebrows never quite came back down.

“Happy Mother’s Day!” said a clearly emotional Justin Trudeau from the stage at the end of the night, as Margaret was embraced by her children from two marriages. Clearly, those were not empty words: Since revelation always comes with risk in political families, this was as remarkable a collective display of affection for a mother as you’re ever likely to see. If any political opponent were to claim that the Trudeaus did not deeply love each over, ample evidence to the contrary was on display here. Why else would they have come? Why else listen?

After all, Margaret Trudeau, reading from a music stand, spoke critically of her workaholic first husband, Prime Minister Pierre Trudeau and the father of Justin and Alexandre, who, she said, did not encourage her latent feminism nor her interest in an independent career, forcing her to throw away magazines sent to her by Gloria Steinem and expecting her to be a traditional political wife, a part she was too young and intelligent to play. She did not paint an unbalanced portrait, nor one lacking in affection for her first husband, a brilliant man of his time, she said, and a leader who moved Canada forward. But if you take away the political trappings around this family, you’d surely allow that it is rarely easy for any child to listen to one half of a divorced pair of parents describe the failings of another. And yet here they, we, all were.

Margaret Trudeau has become a respected mental-health advocate in later life and part of her show, which is quite skillfully co-written by Alix Sobler and given an obviously simple but lively staging by Kimberly Senior, aims to offer advice for living — she advocates for sleep, exercise and self-awareness above all things. Strikingly, some of her most moving stories involve personal kindnesses of the very famous: Jimmy Carter’s supportive hand on her shoulder, or the rigidity that Queen Elizabeth II transmitted to her outstretched arm, so that it could secretly support a Margaret tottering on her heels and about to collapse. These were stories of how we like to think our leaders will behave and, given that truths were being told, it was easy to believe them.

What to make of Margaret Trudeau, this enigma in jeans, white blouse, blue shoes, wife of one prime minister, mother of another, developing a show in Chicago? This storyteller, this witness to as much Canadian political history as anyone?

What she is doing here (as much a podcast as a show) seems healthy, somehow, and certainly as revealing as anything you might ever see of the sheer ordinariness of celebrity political families, none of whom can cheat death or avoid hurt or any of the other stuff that makes up our days. Many of those families have contained rebellious but constrained women, forced to play roles for which they were unsuited; most have gone quietly into the night and into the history books.

But for all her clear nervousness, Margaret Trudeau came up with her own story on Saturday night; it was a reclaiming of a narrative that had always been told by others, mostly by men in magazines.

No reasonable person could begrudge her that nor feel anything but relief that changed times make it possible, if hardly commonplace and even now. And her children coming, openly and en masse, to listen speaks inestimably well of them as human beings.

Chris Jones is a Tribune critic.

cjones5@chicagotribune.com