Whodunit Folks!

teenage mystery novels. they start with 1 and just keep expanding.

there's

Nancy Drew
Hardy Boys
then they join forces:  Nancy Drew & Hardy Boys Super Mysteries
The Three Investigators
The Adventurous Four
The Famous Five
The Five FindOuters
The Secret Seven

what's next?
*The Stumbling Six
*The Elegant Eight
*The Nine Nutcases
*The Tumbling Ten
*The Elusive Eleven
*The Terrible Twelve
*The Thirteen Tricksters
*The Freakish Fourteen
*The Forgettable Fifteen...............