TORONTO - An assignment for a Vancouver Film School student has exploded into a multimillion-dollar action movie opening in theatres across North America this weekend.

Twenty-nine-year-old Seth Lockhead says he wrote the script for the thriller, "Hanna," as his final project in 2005, imagining Cate Blanchett in one of the lead roles.

And roughly six years later, he says he's blown away to see his adventure tale turned into a star-packed film featuring Blanchett, as well as Saoirse Ronan and Eric Bana.

"Hanna" centres on a teenage girl who has been trained by her ex-CIA father to be the perfect assassin.

Lockhead says he only completed half the script by his school deadline, but notes that he still got a good mark.

He finished it several months after graduation, and began contacting Hollywood agents and managers soon afterwards.

The Nanaimo, B.C. native is in New York where he attended a star-studded premiere on Wednesday. "Hanna" opens across Canada on Friday.

Lockhead says he and his girlfriend took the subway to the red carpet debut, and were taken aback by waiting paparazzi.

"My eyes were dazzled by all the flashes and I was blinded," Lockhead says laughing.

"It's not what I think about when I'm writing necessarily, it's kind of more glamorous than I was expecting."