In 1963, Bette Davis was one of four guest stars who stepped into the lead of Perry Mason as Raymond Burr recovered from surgery. As lawyer Constant Doyle, Davis (seen above with William Hopper as private eye Paul Drake) took on the case of a young man accused of murder. Davis was a fan of the program, and it was a coup for the show to land her as a guest star, fresh from her acclaimed performance in Whatever Happened to Baby Jane.
It always amuses me how Della goes meta and partially breaks the fourth wall by saying she feels like they’ve reached the dramatic moment and Perry is about to explain what all the secrecy is about. Sounds like the writer was being very deliberately tongue-in-cheek about part of the show’s formula.