After years of fans begging and practically beating down the doors, Psych the Musical is less than a week away from airing on USA Network.

What can fans expect from this special, two-hour installment, which airs on Sunday, December 15 at 9/8c?

We've seen it, we'll post a detailed review after the episode airs and we've teased fans with a few tidbits below...

• Every regular cast member and guest sings except one.
• An unexpected return takes place, and not the one you're thinking of.
• There will be references to past cases that span all the way back to Season 1.
• Tap dancing will be involved.
• And lots of Skype-ing.
• Tim Omundson has a velvety baritone voice.

We will be live tweeting this singing-and-dancing event and would love for you to join us by following @PsychTVF on Twitter!

Psych Season 8, meanwhile, will premiere on January 8.

C. Charles is a TV Fanatic Staff Writer. Follow her on Twitter.