In the light of such intimacy, the line between performer and audience can become blurred. Having danced with my hand on the fast-beating heart of a sexy bad witch in the height of the action in Faust it's no surprise when Doyle reveals that on occasion performers have been stalked by enraptured punters.
'You invite the audience to fall in love with the characters, to feel like they can touch them. But we have to be constantly on the alert for that, it's all tightly regulated. And props have disappeared. In Firebird Ball someone was walking out in a green ballgown - and she wasn't one of the performers! People just get so wrapped up in what's going on.'
It's been a rapid rise for Punchdrunk - Barrett and Doyle only joined forces four years ago - but Barrett is keenly aware of the pitfalls of falling back on a winning formula. 'Because of the success of Faust the expectations have been raised, so it's a mixed blessing. We don't want people to go: "Oh the old masks again!" So in Red Death we're pushing it absolutely as far as we can go.
'Next we've got plans afoot to do an opera with a live orchestra, which will be something totally different - Punchdrunk is about delivering the unexpected.'
The Masque Of The Red Death, previews from Mon, opens Oct 2, until Jan 12, BAC, 176 Lavender Hill SW11, various times, £20 to £40 (limited availability). Tel: 020 7223 2223. www.bac.org.uk Rail: Clapham Junction