What makes Dave Malloy's weird and wonderful Ghost Quartet a 'gut punch' of a show

It's not often drinking sessions results in many bright ideas - not in my experience anyhow - but for Dave Malloy, sharing a few rounds of Lagavulin with his friends was the catalyst for a one of his most experimental, musically challenging and utterly haunting works.

"I was sat around a table with three of my friends drinking whisky and playing Risk when I looked around and thought, "wow, you're three of my favourite musicians... we should write a show for us!"

And thus, Ghost Quartet began. The follow up to the hugely successful Broadway hit Natasha, Pierre & the Great Comet of 1812, Ghost Quartet blended the strengths of Malloy of his buddies - two of whom had starred in Great Comet - to create the show.

"We knew that we wanted to tell ghost stories, as our musical styles had a certain melancholy so that seemed like the right theme," he tells me on a trip to London, where Ghost Quartet is about to open the new Boulevard Theatre in Soho.

"We talked a lot about what ghosts evoke for us and the stories we're interested in telling, but it's a free narrative. It's very much a puzzle and designed to feel like one. There should be a moment where you go, "ah, that plot is not the main thing here". It's more about the emotion and musicality of it all."

And there's a lot going on in the music, as musical director Benjamin Cox demonstrates as he lists off Malloy's influences for the piece: "It's really folky, there's some heavy rock, some classical, David Bowie, some jazz, Sondheim, some Zelda computer game influences... so it doesn't sound like what we expect from a musical."

Malloy describes the result as a "visceral gut punch", while director Bill Buckhurst, who discovered the musical after paying a visit to Great Comet on Broadway, says the composer has the ability to "penetrate the heart".

Ghost Quartet is a very different piece to Comet. While it was written and performed with Malloy's friends - three musicians with their own skill sets - he has made sure the music is written as freely as possible. Mostly just chords, so any cast could pick it up and adapt it to their skills. And Malloy has made sure the team for this London production has carte blanche.

"I'm so proud and precious of our [original] production, but I don't want to see someone do our version of the show again. I want to see wild interpretations of the same text. That's one of the unique things about the theatrical art form is that you do have this license to radically reimagine things.

"That's why Shakespeare survives; because people have free reign to do what they want. Some of them are a disaster, but some are incredible."

Early indications are that this incoming London production certainly veers towards the latter, which will be a relief to Fawn James and Rachel Edwards, the founder and artistic director respectively of the new Boulevard. With just 160 seats (that's one-third smaller than the Donmar) set in the round (for this production, it's actually one of the most adaptable spaces in the city), the theatre can perfectly suit the intimate feel of the piece. But that's not the primary reason for Edwards' programming.

"For me, the piece is about how we tell and receive stories, so for a new theatre this piece is perfect because that's what a theatre is: a home to stories. But it's also about celebrating this wonderful space we have to tell stories for many years to come, and this incredible score with a sublime cast is a brilliant way to christen any theatre."

And for a piece like this, you will need to have assembled that sublime cast. "We had to find amazing people who could tackle as much as possible of what Dave had written", says Cox, "and we were incredibly fortunate to get musicians who could play some of the instruments Dave had written for originally, and then chuck the rest at them to pick up which has been amazing."

There's all sorts this group had to pick up, including learning the metallophone (like a big metal xylophone), to the Chinese Erhu (a one-string fiddle-like instrument which Buckhurst and Cox admit to being unable to get a tune out of.) What it creates is an intense, weird and wonderful vibe that fills the small space with tension and wonder to complement the otherworldly tales of the musical.

Actor Zubin Varla, who plays most of the keyboard instruments wonderfully sums up why this show works so well in this venue: "The funny thing is the audience will be leaving and heading into Soho, which is a place that's full of ghosts and history. They will have just seen a show that's about connections with ghosts, love, memory, romance, loss...

"It's a show about humanity, and they're walking out into an absolute cauldron of humanity. I hope they take that out with them."

Ghost Quartet is at the Boulevard Theatre until 4^th January.

Ghost Quartet tickets are available now.