The Troubleseekers was a series of thirty-two children's novels written by Annette Billingsley over the course of fifteen years from 1951. The main characters were Humphrey, Jo, Simon, Gertie, and Fatty, but Fatty was not allowed to be part of the Troubleseekers gang as they found him annoying.
The Troubleseekers' oath was printed on each book and read, "I hereby swear to seek out trouble, wherever mysteries boil and secrets bubble. I won't tell adults until the crime is solved, and report back to my friends at the double."
One of the thirty-two books was titled The Mystery of the Haunted Cottage. (PROSE: The Mystery of the Haunted Cottage)