The 1935 film, starring Robert Donat and Madeleine Carroll as strangers on the run, begins and ends in a theatre so a stage version was a neat fit, said actor Mark Pegler during a rehearsal yesterday.

"It's a brilliant adaptation by Patrick Barlow to be able to create all the things that happen in the film on stage," Pegler said. "It's also a great challenge to the actors, designers and everyone to bring it off and I thought I want to be in this, it's fantastic."

Play a clip of The 39 Steps

In the stage show, which opened at the IPAC last night, Pegler reprises Donat's role as Richard Hannay, a Canadian visitor to London who gets unexpectedly caught up in the world of spies and secret agents.

To prepare for their roles the cast of four, including Octavia Barron-Martin, Jo Turner and Drew Forsythe, watched the Hitchcock classic on the first day of rehearsals.

"It was certainly a great help because it gives you a context of what the play is all about and where all the staging and everything is coming from," Pegler said.

"Donat has done a wonderful job but I can't really play it the way he played it, because it's a very filmic sort of performance and quite small and intimate."

To maintain the thrill and suspense of the film, the stage play is very fast-paced with the four actors playing all 139 roles.

The 39 Steps runs at the IPAC until Sunday. Tickets cost $54/$40/$19. Call the box office on 4226 3366 or visit www.merrigong.com.au. Visit www.illawarramercury.com.au to see the actors rehearsing.