The Mystery of the Strange MessagesEnid BlytonThe Five Find-Outers, book 14

Characters in The Mystery of the Strange Messages

3 characters, main characters first.

Main characters

Fatty
Also in The Mystery of the Burnt Cottage, The Mystery of the Secret Room, The Mystery of the Pantomime Cat, The Mystery of the Invisible Thief, The Mystery of the Vanished Prince, The Mystery of Holly Lane, The Mystery of Tally-Ho Cottage, The Mystery of Banshee Towers, Still more Mystery Stories (The Mystery of Banshee Towers / The Mystery of the Burnt Cottage / The Mystery oft the Disappearing Cat)
The Five Find-Outers
Also in The Mystery of the Burnt Cottage, The Mystery of the Invisible Thief, The Mystery of the Vanished Prince, The Mystery of the Missing Man

Antagonists

Mr. Goon
Also in The Mystery of Holly Lane, The Mystery of Banshee Towers, Still more Mystery Stories (The Mystery of Banshee Towers / The Mystery of the Burnt Cottage / The Mystery oft the Disappearing Cat)