"Psych" creative Steve Franks, left, poses with actor James Roday. (Alan Zenuk / USA Network / October 2, 2012)

"Psych: The Musical" is at long last ready for its curtain raiser.

Creator Steve Franks and his writing crew are no strangers to bringing the kooky to the long-running USA Network series--who could forget the re-enactment of "Clue"?

Now, ahead of the launch of its eighth season (which rolls out next month), fans who have long anticipated hearing their favorite fake psychic detective (James Roday) and his best friend/pharmaceutical salesman (Dule Hill) belt out ditties, can now rest easy.

"Psych" will air a two-hour musical episode/movie this Sunday at 9 p.m.-- in which the cast plus guest stars including Ally Sheedy and Anthony Rapp will sing and dance their hearts out.

It's a labor of love for Franks, who moonlights as a musician (and who wrote the show's theme song). He wrote and directed the episode, plus penned the 14 songs with "Psych" music director Adam Cohen.

We talked to Franks about the special.

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Some might say you’re giving “Sound of Music” a run for their money. Early reviews are really liking what you’ve come up with here.

Well, we certainly aren’t going to get the numbers that “Sound of Music” did. Wouldn’t that be something?

And it’s fun that it’s being billed as a movie, not just an extended episode.

I am so calling it a movie because for as long as the show has run, I have always—we have a meeting at the end of the year, with the executives at Universal and they always say, "Hey, what are we doing for next year? What is your plan for next year?" and I always pitch a “Psych” movie.  I was always hoping it’d be a feature film, but at the very least I thought if we stick around after a season is done and shoot two back-to-back episodes and make it a movie. So, this was sort of my way to do the “Psych” movie without having USA Network pay anything else extra for it.

I’m sure they were all for that. And it comes on the coattails of NBC’s “Sound of Music,” which got big numbers but was largely panned by critics and those active Twitter users.  Are you happy about the timing, feel like people are in the mood for it?

It’s really funny because we shot this over a year ago. And [USA] liked it so much they called me and said they were going to make a special night out of it. I was so excited and then they said, "Yeah, we’re going to air it next year.” And I was like, “Whattt?”  There's a big, huge plot point that this was supposed to betting up in the middle of Season 7, that now are built-in continuity errors—or, as I like to say, the basis for a really awesome drinking game. Although, technically, when you get to the very end, there is a way to sort of backwards explain how it could possibly be happening within this time frame in the show.

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And it was something that had been brewing for a while in your mind, right?

It was one of those things. I wrote the theme song. When I sold the show, I had said, "Hey, I’m also doing the theme song.”  And they were like, “Yeah, yeah, sure you are.” And we went in and we put it together and we recorded it. And they said, “Alright, this is fine. We’ll let him do it.” Fortunately, people seem to like the theme song, so from there it was like, “I want to do a whole musical.” This is from the pilot! 

So we talked about it for so many years that we all collectively knew that it was going to be so difficult, but that it meant so much to us that we wanted to get it right, at least within our world. There’s so much effort and joy put into it at the same time because we’re all sort of fulfilling childhood memories, childhood bucket list with this project. Everybody really wanted it to be as great as it could possibly be. I hope we did it right. I know that I love it so much and am so happy with it. I can't stop listening. I can't stop singing the songs. I just got the mixed soundtrack that we’re going to release digitally the day-of…

Yes, “Psych” fans would riot if the songs weren’t made available.

I’ve had to, for the last six months, beat the drum of “are we going to release this?” I was like, “There needs to be a soundtrack. It needs to be this big thing.” I almost felt like I was pestering them to death to do it, but it’s so cool. It’s in my car now and I’m embarrassed because I can’t stop listening to it. It’s so weird because they were these songs that I wrote on acoustic guitar and brought in Adam Cohen, our composer, and months later we’re on the Eastwood Scoring Stage at Warner Bros. with a 50-piece orchestra and all I’ve kept thinking along the way is “this can’t possibly be happening.”

Let’s talk about the story. I assume there needs to be a rhyme or reason to the plot to make it work for a musical element, or can you just take a regular story idea and add some songs to it?