Trailer Park Hamlet.

That's what Emile Hirsch likes to call Chris Smith, the self-contradicting lowlife he plays in William Friedkin's latest thriller, "Killer Joe," which opens here Aug. 17.

Foolish and desperate, Chris is $6,000 in debt, and he's hired the homicidal Joe Cooper (Matthew McConaughey) to murder his mother as part of an insurance scam.

Hirsch sees something Shakespearean in Chris' "constant indecision, his constant going back and forth." The young actor even found himself preparing for the role while working on a real Shakespeare adaptation.

"In the two years before we shot 'Killer Joe,' I was trying to make a film version of a contemporary 'Hamlet,' which we ended up not getting the financing for," said Hirsch when he brought "Killer Joe" to the Seattle International Film Festival (SIFF) in June.

"But studying the play as much as I did — and I watched all the film versions I could find and I watched a bunch of stage versions and read some books on it — I think it really helped me portray Chris. I do."

He hopes there isn't too much of himself in Chris.

"It's tricky to be completely objective about oneself," he said. "To me he's a very morally decayed guy, a very slippery bit of a con man, willing to really do anything to save his own skin, and sell out his mother completely."

Friedkin, who accompanied Hirsch to the SIFF screening (which was part of a festival tribute to Friedkin), said he found the characters' scheming "highly dramatic and true. In many ways, this is a satire of the Norman Rockwell family. I didn't create it. I wish I had."

The script is the second collaboration between Friedkin and playwright Tracy Letts, whose "Bug" Friedkin filmed in 2007. In 2008, Letts won the Pulitzer Prize and the Tony for another play, "August: Osage County."

"I saw 'Bug' on stage in New York and thought it was genius," said Friedkin. "I thought he was a great playwright. He's got a unique voice."

After catching Hirsch's performances in "Milk" and "Into the Wild," Friedkin decided he would be ideal for the movie of "Killer Joe," which was first performed on stage in 1993.

"To me, he's the best young actor around. He's got acting chops as well as a very contemporary feel about the work that he does. And he's very dedicated."

"They didn't tell me much about the script," said Hirsch. "They just told me that Billy was directing. So I went into it totally blind. I hate synopses and little plot lines that agents pitch." He's also not a fan of trailers that give away too much.

"So I read 'Killer Joe,' and I didn't know what to think. It was a very odd experience reading it — much akin to the feelings I had watching the film the first time: a mixture of comedy and drama and confusion and alternating revulsion and terror — which I love. I think that's the strength of it, the kind of places that it goes."

"You can't comment on your character when you play a role," said Friedkin. "(Emile) could not portray Chris AND condemn him. An actor must find something of the character in himself in order to go there, no matter who it is.

"If you're playing Charles Manson or Hitler, you have to find your inner Hitler. You can't pass judgment on the character you're playing while you're playing it.

"I'm sure everybody would love to play a heroic figure, but that's not necessarily the case with the best actors. They would rather play the villain. Some of the greatest performances are the villains."

Unsavory characters tend to dominate Friedkin's most popular films. He won an Oscar for directing "The French Connection," in which cops and criminals are almost interchangeable. His biggest hit, "The Exorcist," imagines a child possessed by the devil. On television recently, he's done some "CSI" episodes.

"I've made only 15, 16 films in 45 years," said Friedkin. "A lot of times I made some false starts because I couldn't find the story, and so I abandoned (those projects). Often I'm intrigued by a set of characters, but then the story doesn't work out."

"The French Connection," for instance: "I had four or five scripts. I wound up writing the script on the set."