New musical Betwixt!, currently charming audiences at Trafalgar Studios 2, is celebrating its recently extended run (to 10 September) with a free performance for select members of its “ever-growing army of Twitter fans”.

The special “Be-Tweet” performance will take place on 22 August and to get a ticket, entrants need to be following @BetwixtMusical on the social network and tweet the following between now and the 18 August: I’m a #betweeter and I should come to #betwixt because:

Producer Christopher D Clegg explains: “You then have to post a picture/video/audio file/blog/vlog/drawing that sums up why you love Betwixt! and why you should come to this special performance. You can use twitter, tumblr, facebook, youtube, flickr - anything that can help you get your point across.”

Telling the story of New York writer Bailey and his flamboyant roommate Cooper who are catapulted into a strange enchanted world, the show promises "sitcom-styled dialogue and a toe-tapping score". The cast includes former Blue Peter TV presenter Peter Duncan, Broadway's Ellen Greene, Wicked's Ashleigh Gray, History Boy Steven Webb and newcomer Benedict Salter.