Updated: Here is a really good article summarizing and criticing Girl Sleuth. art
I read this a few years ago. Its called Girl Sleuth. Its the story of the writers of Nancy Drew. One became a reporter in Iowa and the other became CEO of the publishing company. They were the main writers. The book culminates with the TV series in the seventies oh the CEO, although she may have been retired, was furious with the actress and show. The actress was fired after her posing in Playboy. Look up about the Iowa writer, they need to makea movie about her. Or movie on this book.
What is so interesting also is that these writers were not allowed to give their names. This company which published Hardy Boys and Bobbsy Twins amazingly got away with this. The closest today with house names is under Harlequin with their Gold Eagle branch. They use house names for Deathlands and Outlanders along with making Don Pendeleton who wrote and created The Executioner series into a housename. Harlequin in their page listing the company info with copyright has a line labeled "with special thanks to (name)". The name is the person who wrote it.