What do you need to really sell a song?

A sucker who will buy it.

So says Sister Robert Anne in Dan Goggin's Sister Robert Anne's Cabaret Class, an evening of shtick now running at the Society Hill Playhouse. Judging by Goggin's career, he has found no shortage of buyers, having written eight nun-themed shows or sequels to his 1985 Off-Broadway hit Nunsense.

The character of the Brooklyn-born, street-smart Sister Robert Anne appeared in the original. In this latest iteration, Goggin returns to cabaret format, where Nunsense began before becoming a two-act staged musical.

Here, Sister Robert Anne (Christine Mild) instructs the audience in "everything she knows about being a cabaret performer and putting on an act." She uses a blackboard and desk (thankfully not a clicker) to answer numbered questions: What will you wear? How will you do your hair? What will you sing?

Most of her songs consist of lyrics (written by Goggin) about singing, performing, and longing to be a star. And while Goggin's music gives Mild a chance to show off her impressive voice, his book forces her to interrupt all but two numbers in ways that only embarrass - for instance, ruining a series of belts that cap a touching song about childhood with a Streisand impersonation.

Speaking of impersonations, Mild delivers imitations of Streisand, Judy Garland, Ethel Merman, and Daffy Duck (not a typo). Her versatility shines through with a sincerity that knows no bounds. In a program that also includes an Avenue Q-style puppet number, three scenes of audience participation, a Q&A session, and pop culture references from 50 years ago (or more, I wasn't alive then), she delivers every line earnestly, like a saint sacrificing her talent on an unworthy pyre.

When she sings, when she really gets a chance to unload that shimmering voice in the evening's two genuine, uninterrupted numbers (particularly the penultimate "I Left Him There"), she completely captivates. As someone who's a sucker for a gorgeous voice, I would have bought her act anytime. Anywhere else.


Sister Robert Anne's Cabaret Class

Through Dec. 29, Red Room Cabaret Theater at Society Hill Playhouse, 507 S. Eighth St.

Tickets: $35

Information: 215-923-0210 or www.societyhillplayhouse.org