Wikipedia
Mystery! (also written MYSTERY!) is a television anthology series produced by WGBH Boston for PBS in the United States. The series was created as a police/crime drama spin-off to the already established PBS show Masterpiece Theater. From 1980-2006, Mystery! aired mostly British crime series purchased from or co-produced with the BBC or ITV and adapted from British mystery fiction. In 2002, due to pressure to include more American material, a series based on the novels of US mystery writer Tony Hillerman was produced, but the vast majority of Mystery! programming has always been and continues to be British literary adaptations co-produced with UK-based production companies.
In 2008 PBS combined Mystery! with its predecessor Masterpiece Theater under the umbrella title Masterpiece, which includes the sub-brands Masterpiece Classic, Masterpiece Mystery!, and Masterpiece Contemporary.