Live theatre was once the main entertainment medium in the United States and the United Kingdom. The preeminent dramatists and actors of the day wrote and performed in numerous plays in which crime was a major plot element. This remains true today, especially with the longest-running shows such as The Phantom of the Opera, Les Misérables and Sweeney Todd. While hundreds of books have been published about crime fiction in film and on television, the topic of stage mysteries has been largely unexplored. Covering productions from the 18th century to the 2013–2014 theatre season, this is the first history of crime plays according to subject matter. More than 20 categories are identified, including whodunits, comic mysteries, courtroom dramas, musicals, crook plays, social issues, Sherlock Holmes, and Agatha Christie. Nearly 900 plays are described, including the reactions of critics and audiences.