A voice in the dark then asks if she still does – cue an amusing lesson in pot and paranoia.
All of this wouldn't sound half as strange had we gathered to see Martha do her thing in a sweaty boozer. But we're in a church. And there is no bar. Just one woman, an acoustic guitar and a hell (sorry) of a voice.
I know what you're thinking: Martha in a church ... isn't she the chick who had that song about her dad? Rufus's little sister – the girl who sang that angry tune with the bold title?
And yes, Martha (36) is the jaunty, Canadian-American artist that gave the world Bloody Mother F***ing A**hole. Tonight, however, she has decided to sideline the track in favour of some cleaner and – let's face it – far better material, a lot of which stems from her third studio album, Come Home to Mama.
A masterclass in solo presentation, Martha's decision to tour alone following the creation of what is, at times, a full-band record, might seem odd. Maybe it's more to do with economics. Whatever the case, she greets the challenges of trying to please a fully seated crowd by herself head on. The results are mesmerising – not least because of the chosen venue.
Martha's star might never shine as bright as her brother's, and she might not be quite as prolific a songwriter (she continues to cover her mother's material), but again, it's that boundless, superlative vocal of hers that stands out.
It's her finest instrument and she's not afraid to stretch it in ways that might seem a little strange or even comical (Can You Believe It, Four Black Sheep).
On All Your Clothes, a poignant, graveside conversation with her late, folk- artist mother, Kate McGarrigle, we're reminded nobody does acoustic heart-ache better than Martha Wainwright.
That isn't to say that she doesn't have fun. Indeed, this is a performer who could very easily have opted for a career in stand-up, such is Martha's ability to tell a great story while tuning a guitar.
It's a wonderful evening of live music – and in a rather beautiful setting, too.