The Case of the Terrified Typist is a 1956 Perry Mason mystery novel by Erle Stanley Gardner, featuring a frantic temporary typist who disappears, leaving behind diamonds and a trail that leads Mason to defend a gem importer accused of smuggling and murder. The plot revolves around Mason's efforts to find the missing typist, who holds the key to a complex criminal conspiracy involving smuggled gems, a potential suicide, and a murder case. It's known for its classic courtroom drama and is part of the long-running series that inspired the HBO show.