Sam Holcroft’s A Mirror is a play-within-a-play that becomes a play-within-a-play-within-a-play, and on the way asks “What is a play supposed to be?” Set in an unspecified, post-Communist Balkan country, it focuses on a government ministry that heavily regulates and censors art. Adem, a car mechanic, writes a play made of dialogue that he transcribed verbatim in a bar; it includes drinking, swearing, and sex. His play is immediately banned, but lands him a mentorship with the deputy culture minister, Čelik. In the role of Čelik, Jonny Lee Miller (The Crown, Elementary) has won raves. —Jensen Davis