TORONTO -- Acclaimed Canadian playwright Judith Thompson takes to the professional stage as a performer for the first time in 35 years Tuesday as she stars in her disturbing new play based on the Ashley Smith tragedy.

In the emotionally exhausting one-woman show "Watching Glory Die," Thompson, 59, explores the horrors of the teenager's inexorable, downward spiral to death behind bars.

"I was just absolutely haunted and devastated by what had happened to her," Thompson said in an interview during a recent rehearsal break.

"When there's something I don't understand and I'm outraged, the only way I can express it is through writing a play."

Although fictionalized, the play's three characters are immediately recognizable to anyone familiar with the story of 19-year-old Smith, who choked herself to death in an Ontario prison as guards stood by and watched.

First jailed as a 15-year-old old for throwing crab apples at a postal worker, she had been shunted to prisons around the country, spending almost all her time in solitary confinement. Last December, an exhaustive inquest declared her death a homicide, based on management orders to guards to stay out of her cell as long as the teen was still breathing.

"I was compelled to address the horror that Ashley Smith endured," said Thompson, a multiple-award winning playwright of such works as "White Biting Dog," "Lion in the Streets" and last year's "Thrill."

"There are Ashleys all over the world and many here, and the public does not know what's being done in their name."

Thompson's powerful writing and acting skills are on full display as she throws herself for a non-stop 75 minutes into roles that stretch her versatility to the max.

Bringing the teen back to life through Glory involves a roller-coaster emotional journey.

There's the sweet teen girl fantasy of being noticed by a hot guy; the breaks from reality as Glory struggles to cope with the steel-cold realities of her prison isolation; and the raw rage:

"I was only kidding," Glory protests as guards once again restrain her.

"Stop (expletive) squeezing my neck. It hurts. I can't (expletive) breathe."

In portraying the teen's mom, Thompson captures Coralee Smith's pain with startling authenticity.

"Every child born is born to all of us. We are all responsible," Rosellen (Coralee) soliloquizes in her East Coast lilt.

"These things go on in the dark, in the shadows, and we don't even know until they affect us in some way."

"What she's been through, it's just unimaginable," said Thompson, a mother of five who has met Coralee Smith.

"Watching Glory Die" explores the dilemma that guards faced in the Smith case as they dealt with the increasingly distressed inmate, who had choked herself scores of times with ligatures. Management had concluded Smith was simply an attention-seeker and disciplined them for intervening.

"In a way, the guard is all of us -- it's about what would I do?" Thompson said.

"Do we have the strength of character to disobey orders that may cost us our job?"

Thompson does not shy away from Glory's harrowing last moments, her heaving gasps for breath as her life ebbs away.

Outside the cell, guards debate whether she's still breathing, whether to go in. Until it's too late.

"I have to go there. I have to try. Because she had to go there," Thompson said.

"I owe it to Ashley. I want to give her what I can."

Overall, however, it's difficult to escape the potent political message of "Watching Glory Die," born of Thompson's outrage and disgust.

The system destroyed Smith, she said. And it happened where least expected.

"The impossible is happening in our country," Thompson said.

"Watching Glory Die" -- directed by Ken Gass -- previews Tuesday and premieres Wednesday at Vancouver's The Cultch, where it runs until May 3.

The Canadian Rep Theatre production then moves to Berkeley Street Theatre in Toronto for its premiere on May 17 -- after two days of previews -- and runs until June 1.