Jason Cole or Ian Price? A brilliant neurosurgeon or his charming, manipulative alter ego? That’s the choice audiences will have to make when they tune in on Thursday to the premiere of NBC’s new series, Do No Harm, starring Steven Pasquale.

“What actor wouldn’t love to have the acting smorgasbord that is getting to take on two violently different personalities?” Pasquale asks.

On the new show, he plays Jason Cole who, as with Dr. Jekyll in Robert Louis Stevenson’sclassic novella, turns into the reprehensible but alluring alter ego, Ian Price, every night at precisely 8:25. Unlike Mr. Hyde, Price isn’t quite the embodiment of evil, but is bent on throwing obstacles in the path of Dr. Cole.

Rounding out the cast of Do No Harm are Phylicia Rashad as Dr. Young, the head of neurosurgery at the hospital where Cole works, and Alana de la Garza as Dr. Solis, a co-worker in love with both Jason and Ian, who is clueless to his bifurcated nature.

“What we really wanted to experiment with in Do No Harm is rather than the classic Jekyll and Hyde sort of version where one’s a monster and one’s not, it’s two guys where there’s a lot more gray area so that all of the other characters in the show – the tension comes from when they’re interacting with Jason/Ian, and they don’t know who they’re dealign with,” explained Pasquale. “We’re hoping the audience falls in love with Ian, and then hates themselves for it.”

That might not be as hard as it sounds. Pasquale employs no prosthetics or cgi to make the transition from one character to the other, but relies heavily on physical contortions.

“All of those scenes are difficult to shoot in that, for no other reason, they give me back cramps,” he griped. “It involves a lot of shaking and intense amounts of body shivering, so it’s not so easy on the back and neck.”

A veteran of stage and television, Pasquale is best known for portraying Sean Garrity on the hit series, FX’s Rescue Me, that show’s main source of levity. So, what’s he doing in the lead role of a thriller?

“I played a completely comic relief character on Rescue Me for such a long time that I was really itching to get back to doing something dramatic,” he explained.

Pasquale first became known to TV audiences playing a love interest to David in HBO’s Six Feet Under, and went on to star as surgeon Dr. Bellows on last year’s A&E mini-serie, Coma. So, maybe the leap from comedy to thriller is not such a great one after all. According to Pasquale, he was destined to find himself in someone else’s shoes from a very young age.

“I was just a kid who liked to imagine what it would be like to be someone else,” he recalled. “It’s crazy, but you know what, an actor’s life for me.”

Do No Harm premieres Thursday at 10PM on NBC.