The actor Michael Mears got the idea for The Mistake in 2002, after reading an article that interviewed two people: the pilot of the plane that dropped the first atomic bomb and one of the bomb’s survivors. The play came together a few years later, when he learned about Leo Szillard, a nuclear physicist who had helped develop the atom bomb and was haunted by guilt. The play focuses on these three characters and how their stories intersected on August 6, 1945, when the bomb was dropped on Hiroshima. After a sold-out February run, the show is now on at Arcola Theatre. Mears himself stars as the Szillard. —Jensen Davis