"Alfred Hitchcock's The 39 Steps" adapted by Patrick Barlow, at Alley Theatre in Houston, through Sept. 3. Pictured: Bruce Warren, Mark Price, and Elizabeth Bunch. (Photo by Christopher Diaz)

Onstage This Week: July 31-Aug. 6

From a sadistic dentist to international spies, from Oregon to Texas, here is a sampling of what is playing this week at select theatres around the country.