SANTA CLARITA, Calif. — What's TV's favorite obsessive-compulsive detective doing in a mosh pit surrounded by sweaty, skimpily clad rock fans jumping around to very loud music at an outdoor concert?

And what's he doing wearing a buttoned-up shirt and brown wool jacket in the broiling sun while trying to catch a beach ball bouncing above the throng?

USA Network's Adrian Monk may have phobias about germs, crowds, noise, heights and more, but when there's a crime to solve, he somehow delivers and the beach ball is a vital clue to a murder committed in — cringe! — a portable toilet.

"Monk doesn't want to jump. His heels come off the ground, that's about as high as he'll go. He'll reach up, but he wouldn't leave the ground," says Tony Shalhoub of his character as he sits in the shade during a break.

The episode shooting this day, titled "Mr. Monk Goes to a Rock Concert," is part of the series' fifth season, which debuts tonight with an installment called "Mr. Monk and the Actor."

That episode features Stanley Tucci as a famous thespian shadowing Monk because he will be portraying him in a movie. The method actor's efforts to get inside Monk's head and ape the mannerisms of the very neurotic but brilliant sleuth create enormous problems.

Series creator and executive producer Andy Breckman says the challenge is to "come up with stories that are as much fun as Monk is."

"What we love doing is throwing Tony Shalhoub curve balls and seeing if he can hit them. And he can. Like with the portable toilet, a crime scene that Monk could never get close to. That was fun to write, but it was even more fun to think about how Tony will make it his own," says Breckman.

"He actually mistakes it for a phone booth and kind of backs into it," Shalhoub grins.

Of course, Monk is not alone is his adventures. Captain Leland Stottlemeyer (Ted Levine) and Lt. Randall Disher (Jason Gray-Stanford), the San Francisco cops who need Monk's brain to help them solve crimes, are at the rock concert, too. So is Natalie Teeger (Traylor Howard), Monk's personal assistant and minder.

Howard joined the cast in the middle of the third season after the abrupt departure of Bitty Schram, who had played Sharona Fleming, the nurse who helped Monk cope with his disorders and dilemmas.

"Sharona was a great assistant, but she was kind of brittle and very annoyed by Monk, so we thought, 'What if there was a softer, more affectionate assistant, someone who would add a little sweetness to the mix,"' says Breckman, explaining the process behind the creation of Teeger.

Howard, an actress with extensive experience in commercials and sitcoms, hadn't seen "Monk" when she first auditioned for the role of the young widow who is raising a preteen daughter, Julie (Emmy Clarke.)

Howard has a sensible view of her impact, which she believes helps the series have a "little more of a reality base." She says entering an established popular show was no problem for her personally, until she realized how "beloved" the Sharona character was. But good reviews and the show's continued successful ratings eased the transition.

"He's a handful, he's a definite handful," laughs Howard about the ultra picky but endearing detective. But she notes there's a lot of respect in the relationship because, like Monk, Teeger has experienced the loss of a spouse.

"Also, she's probably kind of bored in her life and it's probably the most exciting thing she's had going in a long time," she says.