Eric McCormack and Rachel Leigh Cook Eric McCormack and Rachel Leigh Cook

Daniel Pierce is that guy. The one you flee as he argues with the air, or conducts an imaginary orchestra while he waits in line. But take a deeper look: You'll find a complicated man who also delivers beguiling lectures on the intricate workings of the brain and helps the FBI solve complex cases with his expansive knowledge of human behavior.

M.D., Ph.D. and schizophrenic, Pierce is the brilliant and damaged hero of Perception, TNT's new procedural-with-quirks. He's a mash-up of Monk, House, Patrick Jane and Sherlock Holmes, not to mention cousin to schizophrenic genius John Nash in the Oscar-winning A Beautiful Mind, an inspiration for Perception cocreator Ken Biller. "I wanted to take a character like Nash and put him in a believable situation where he could use his expertise to solve crimes," he explains, "while also exploring his struggles."

Casting against type, he chose Eric McCormack to play Pierce. "The show's not a comedy, but I wanted an actor who is intelligent and can be funny." As it happens, the Emmy-winning actor was looking for a show "very far" from Will & Grace. "I like being out on the edge a bit," says McCormack.

At their cores, however, the character-driven crime show and the beloved sitcom share a common element: tolerance. "Mental illness is the last frontier," says McCormack, whose long-running comedy arguably helped foster gay acceptance in the U.S. "The gay thing is part of everyday life now on a show like Modern Family, but mental illness is still full of stigma. Maybe it is time for that to change."

When the series opens, Pierce is more or less holding it together, relying on his assistant, Max (Arjay Smith), and best friend, Natalie (Kelly Rowan), to keep him on a routine. That calm is upended when former student-turned-FBI agent Kate Moretti (Rachael Leigh Cook) asks him for help with a case. "I don't ever get the opportunity to play tough," says the diminutive Cook (Psych), "so when this role came around to be the person packing heat, I couldn't pass it up."

Pierce agrees to help, though his inability to distinguish between a real-life person and a hallucination makes interviewing witnesses tricky. "Part of the fun is trying to figure out if the person Pierce is talking to is real, so we try to mix it up," says Biller. "Sometimes the viewers will be [in on] Pierce's delusions and other times — when he sees, say, Joan of Arc — the mystery is why this hallucination?" As McCormack puts it, "His brain is his best friend and his worst enemy."

MacArthur genius grant recipient Elyn Saks understands Pierce's challenges. A law professor who consulted with McCormack about his role, she wrote a critically acclaimed memoir, The Center Cannot Hold, detailing her life with schizophrenia. "I love the show, and it's true that Pierce's symptoms can tell him things about himself and other people," she says. "The character is very [realistic]."

Like McCormack, Saks hopes Perception "destigmatizes schizophrenia by portraying someone who has disabilities but functions at a high level. It can put a face on the illness."

Perception veers into more familiar TV territory with the relationship between Kate and Pierce. Soon after she reaches out for his help, the two realize they want each other in a more personal way. "He [continues] to do this job because of Kate," McCormack says. "He can't say no to her."

A number of obstacles lie in the way of their hooking up — beyond his condition. For one, there's a charming visiting professor (Battlestar Galactica's Jamie Bamber) with a yen for Kate. And Pierce has confidante Natalie, for whom he harbors romantic feelings. "We see a very unusual triangle play out among [Kate, Pierce and Natalie]," Biller promises.

The cases Pierce and Moretti work are unusual, too. "Going back to my science-fiction days on Star Trek, my favorite episodes dealt with strange alien behavior," says Biller. "This is an opportunity to take on strange human behavior." So Pierce diagnoses such phenomena as face blindness (people who really never recognize a face) and psychotic suggestibility.

But McCormack is most interested in the debates the show sparks: "I love that there will be conversations about it beyond just the whodunit." Now that's giving us something to talk about.

Perception premieres Monday at 10/9c on TNT.

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