As actresses Gwen Langenberg and Silke Hundertmar - who star as sisters in the harrowing theatre show playing at Canberra Theatre this week - gave silent screams to the camera, they barely noticed the poor tradie's response.

Probably because they've been terrifying audiences across the world for more than four years.

Horror is the creative vision of European theatre-maker Jakop Ahlbom, and uses physical theatre and cinematic-style special effects to tell the story of two sisters: one alive (Hundertmar) and one dead (Langenberg).

After years apart, the sisters are reunited in their former family home to confront the atrocities of the past.

There is no dialogue in Horror; only an unnerving soundtrack and, according to Langenberg, a series of "scenes that defy belief".

Langenberg said Linda Blair's Regan from The Exorcist and Daveigh Chase's Samara from cult horror movie The Ring provided the inspiration for her satanic, childlike character.

Like Blair and Chase once did, Langenberg, a trained dancer, spends a lot of time performing in contorted positions.

"At many points I take very extreme positions in the performance and if you do them a lot of times in a row, that's quite demanding," she said.

"There are a lot of scenes where I'm a kid and I get punished, so all the time I'm getting punched and I'm flinching. My body doesn't know the difference between 'oh it's not real' or not - it just reacts."

Both Langenberg and Hundertmar have regular massages to deal with the physical stress of emulating violence and fear on stage. But both women - who have partners and children at home in The Netherlands and Holland, respectively - are addicted to the response the terrifying show elicits from the audience.

"The reaction is different right across the world," Hundertmar said.

"In Germany and Belgium they're scared and they're so quiet. But in England, especially London, and in Australia, the audience is always like, 'Whoa' and talking a lot.

"There's one scene that's quite disgusting - in London they went insane."

The stars of Horror have yet to guage the response from an Asian audience; the show was due to be staged in China earlier this year but the season was cancelled for censorship reasons.

"It's something you have never seen before," Langenberg said.

"It doesn't matter if you don't like horror, but what you see on stage ... you are trying to figure out in your mind, how could this possibly happen in front of my eyes?

"It's not television, its not a movie, so what just happened?"

Horror, Rated M15+, September 11-15, Canberra Theatre. Tickets and more information at www.canberratheatrecentre.com.au