Tyrone Warner, CTV.ca

TORONTO — "Criminal Minds" star AJ Cook tells CTV.ca that her first day on set she was "sweating bags" thanks to nerves.

"In my very first scene I had to bust into the room and take charge and dominate," laughs Cook.

"I just had to rush through the room, speaking a hundred miles an hour, ordering everyone around. I was so nervous, and I don't even know how I got through that day."

Cook plays Jennifer "J.J." Jareau on CTV's "Criminal Minds." The series follows an elite group of federal investigators called the "Behavioral Analysis Unit," who solve mysterious crime sprees.

The 29-year-old says the experience she's enjoyed most on the show is crafting her character over the course of the series.

"When I came on, she was just black and white on a page. There was no description, and nothing really to her," says Cook.

"It's been a fun process working with the writers and finding who she is."

Starring well-seasoned actors like Shemar Moore, Thomas Gibson, and recent addition Joe Mantegna, Cook thinks the key to the success of "Criminal Minds" is all in the cast's chemistry.

"When you get a cast together, you hope it does well. And sometimes it works, and sometimes it doesn't," says Cook.

"It's interesting because we do have a pretty large cast. At the same time, it doesn't feel crowded. There seems to be room for everyone, without us talking over one another."

According to Cook, the appeal of the sometimes disturbing drama lies in the dark psychology that explores exactly what makes a murderer tick.

"We come out of the gate the same, pretty much, from birth. It's interesting to see what kinds of things happen to a person to make them that way," says Cook.

The actress acknowledges that this intellectual edge hooks in female viewers. Cook recalls one fan telling her that she loves to watch, but has to "look away" when the show gets violent.

"I think that's what people are drawn to," says Cook.

Besides the intellectual aspect, the actress says there's another reason women tune in.

"Shemar Moore is a dreamboat!" exclaims Cook.

"I think one of the first things I said to him was 'alright dude, I'm just going to get this out of the way, I grew up watching you on the soaps.' He was so gracious with it all, and he was really, really cool about it."

Cook, a native of Oshawa, Ontario, got her start on Canadian television, with a guest role in "Goosebumps." The actress originally trained as a dancer before she turned her attention towards acting.

Considering Cook's background, the question remains to be asked: Will she be appearing on an upcoming "Dancing with the Stars" competition?

"You know what? I probably wouldn't because I would kill everyone, because I'm that good," laughs Cook.

"Criminal Minds" airs Wednesday nights on CTV. Check your local listings for details.