Paulo Costanzo

Royal Pains fans are already very, very familiar with the cast's mad rapping skills, but who knew that HankMed & Co. could really carry a tune?

In this exclusive sneak peek, the cast of the USA series gets musical for the final chapter of Evan's Campaign Chronicles  webisode series.  The episode was a "labor of love" for Paulo Costanzo, a self-professed musical-theater aficionado. "My first acting role ever was Tony in West Side Story in high school," he tells TVGuide.com.

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Costanzo not only starred in and directed the webseries, but he also wrote the original song with composer Charlie Barnett after the show couldn't get the rights to the Les Miserables song they wanted to use. "Finally I just got frustrated and wrote the whole song — surprising myself," he says. "I've never actually written a song before and within a week, we were shooting it, which was really insane."

Fans will be surprised to hear just how many members of the cast can really sing. "Brooke [D'Orsay], [was] terrified to sing — I knew she could sing if forced to," he said. "In the recording studio, I put her through the paces."

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Costanzo was even able to wrangle Royal Pains' guest stars like Emmy nominee Frances Conroy. "She, as a favor, decided to do my little musical," he says. "She has arguably the best part in the whole thing and she was really game."

Although this is the final of five webisodes, this will only be the beginning of Royal Pains' musical productions if Costanzo and Royal Pains' executive producer Michael Rauch have any say. "Next year, fingers crossed, somehow they'll allow me and Michael to put together another musical number in the actual show," Costanzo says. "I'm going to say this on the record just to hold [Michael] to it: He said that if we do one, he'll let me write it."

Check out a sneak peek of the musical webisode and check back here after Wednesday's episode to see the full webisode.