Imagine you could go back in time and stop the assassination of U.S. president John F. Kennedy.

That's the premise behind "11.22.63," the nine-hour miniseries based on the bestselling novel by Stephen King. The first two hours premiere Wednesday on Super Channel.

James Franco stars as Jake Epping, a high school teacher who follows a portal into the past which lands him in Texas in the early '60s. There he meets Lee Harvey Oswald (Daniel Webber), the gunman who -- according to the Warren Commission -- acted alone in gunning down the 35th U.S. president.

A complication for time-traveller Jake is falling in love with librarian Sadie Dunhill (Toronto's Sarah Gadon). Chris Cooper, Cherry Jones and Josh Duhamel also star.

King fan J.J. Abrams ("Lost," the new "Star Trek" movies) is executive producer. He praised King and screenwriter Bridget Carpenter ("Friday Night Lights") for crafting a compelling series of episodes that "grab you by the heart and grab you by the throat and just drag you through this thing."

"Where were you when Kennedy was assassinated?" is a question only boomers and those born earlier can answer now. Of the main cast of "11.22.63." only Cooper, 64, and Jones, 59, are old enough to remember.

"There are a whole bunch of people now that are unfamiliar with the Kennedy assassination and some of the questions that are still being raised," Cooper told reporters last month in Pasadena, Calif., at the winter TV press tour.

"I wasn't alive when it happened," said Franco, 37, "but it's a big event."

Franco had read King's book and tried to option the story before learning Abrams had beaten him to it. As central character Jake, Franco is in almost every scene and even directed one episode.

For his generation, Franco says, "it feels sort of like Marilyn Monroe or James Dean or something like that." He believes the King novel and this miniseries offer "a fresh way in. We're not exactly telling a history lesson."

The assassination is two lifetimes ago for Gadon, 28. She told reporters at the press tour that, being Canadian, "it's not a big part of my country's history."

Other Canadians in the production had a different perspective.

Shauna MacDonald, who plays Oswald sympathizer Jeanne de Mohrenschildt, is originally from Antigonish, N.S., and born less than a decade after the assassination. She understands that "it was such a hopeful time, and then, the end of a possibility."

For Gadon the millennial, however, working on the miniseries was truly "a process of discovery."

"I knew about the assassination, but I didn't know in detail the conspiracy theories that existed," she said. Gadon, for example, saw the famous Abraham Zapruder film -- an eyewitness recording of the assassination -- for the first time while researching her role.

She spoke to her parents about the assassination but doesn't feel "a lot of young Canadians of my generation know much more than just the basic facts of what's printed in the history books."

News that production would be based in Toronto (aside from scenes shot in Dallas at the assassination site in Dealey Plaza) was a big draw for Gadon. Finally she could work in her hometown.

"I thought, 'I'm going to see all my friends and family,"' she said. Instead, most of the production took place in nearby Hamilton, Ont. "My dreams of a summer project in Toronto were quickly shattered."

Gadon previously worked on two David Cronenberg films as well as the historical series "World Without End." She had just worked in New York on the feature "Indignation," which is set in the '50s, before stepping straight into the '60s with "11.22.63."

Gadon and MacDonald praised the attention to detail that went into both the costume and set design of the series, singling out Abrams' favourite costume designer Roland Sanchez.

"Roland can create an era and transform you too," says MacDonald.

Gadon agrees. "I wore a girdle every single day when we shot this piece and that changes the way you move," she says, especially in dance scenes. "I did a full Lindy Hop dancing in a girdle."

Gadon feels the way you dress in a series definitely informs the performance. "I'm wearing Spanx today," she said at the "11.22.63" press session, "and I can tell you that it's a lot more comfortable than a girdle."