This series, also called the Five Find-Outers and Dog, is by Enid Blyton. It is one of Enid Blyton’s mystery adventure series about a group of children and a pet. In this series, there is a group of five children and a Scottie dog named Buster. Most of the children in the group go to boarding school, except for the youngest, and they all solve mysteries together during school holidays.
The village policeman, Mr. Goon, is antagonistic to the children because he is embarrassed that they find the solutions to crimes before he does. However, the children have an ally, Inspector Jenks, who makes Mr. Goon listen to them.
The Children:
Frederick Algernon Trotteville – Nicknamed “Fatty” by his friends because his initials are FAT and he’s kind of stout, although he’s not completely happy with the nickname. He becomes the leader of the group after Larry passes the title to him in the third book. He is Buster’s owner, and at first, the others mainly let him join their group because of his dog. Because Frederick/Fatty is an only child, his parents and other wealthy relatives give him generous amounts of money, so he shares with the other members of the group and buys disguises and other items they need in their investigations. He loves experimenting with disguises and wants to become a professional detective eventually.
Laurence Daykin – Called Larry by his friends. He is the oldest member of the group. At first, he is the leader of the group, but then, he lets Fatty have that role.
Margaret Daykin – She is Larry’s younger sister, and her friends call her Daisy. She is the idea person of the group, and in fact, forming the Five Find-Outers was her idea. She is the same age as Fatty and Pip.
Philip Hilton – Called Pip by his friends. He is the same age as Fatty and Daisy, and he also has a younger sister, who he likes to tease. His parents are more strict than the others, and they don’t really approve of the children’s detective activities.
Elizabeth Hilton – The other children call her Bets. She is the youngest of the group, four years younger than her older brother Pip and most of the other members of the group, but they’re still friends with her and let her accompany them during mysteries. She hero-worships Fatty, and he also likes her and appreciates how observant she is.
Books in the Series:

The Mystery of the Burnt Cottage (1943)
The children discover who set fire to Mr. Hick’s cottage.
The Mystery of the Disappearing Cat (1944)
A friend is blamed for the theft of a valuable show cat.
The Mystery of the Secret Room (1945)
Fatty begins seriously studying disguises and other detective skills, and he becomes the leader of the group. The children discover that an apparently empty house has a secret room that is furnished and being used by someone for something. They try to figure out who owns the house and who’s using it.
The Mystery of the Spiteful Letters (1946)
A mysterious person starts sending anonymous nasty letters to people in the village where the children live. Who is doing it, and why?
The Mystery of the Missing Necklace (1947)
The children investigate a series of jewel robberies.
The Mystery of the Hidden House (1948)
After a mix-up involving Mr. Goon’s nephew, Ernest, where the other children accidentally mistake him for Fatty, Mr. Goon persuades the children’s parents to make them stop investigating mysteries. To get even, the children decide to trick Ernest (called Ern for short) into thinking that they’re investigating a fake mystery, but they end up finding a real one. This story takes place around Christmas.
The Mystery of the Pantomime Cat (1949)
Someone has broken into the safe at a theater, and the suspect is someone dressed in a cat costume from a pantomime.
The Mystery of the Invisible Thief (1950)
A house burglar mysteriously disappears without a trace. Who was it, and how did he do it?
The Mystery of the Vanished Prince (1951)
Fatty returns from a cruise and brings some exotic foreign costumes for his friends as presents. While they’re dressed in these costumes, the children encounter Ern and Mr. Goon, and as a joke, they convince them that they’re actually royal friends and relatives of a foreign prince who is actually visiting England. When the prince disappears, the children’s prank confuses things until the admit the truth and join the search for the missing prince.
The Mystery of the Strange Bundle (1952)
The night Mr. Fellows’s house is robbed, he is seen running away with a large bundle. Where did he go, why did he run away, and what’s in that strange bundle?
The Mystery of Holly Lane (1953)
The children are practicing their detective skills by putting on disguising andshadowing people when they discover that the house of a blind man has been robbed.
The Mystery of Tally-Ho Cottage (1954)
The Mystery of the Missing Man (1956)
The Mystery of the Strange Messages (1957)
The Mystery of Banshee Towers (1961)
In an effort to get the children to stop looking for mysteries to solve, their parents send them sightseeing, but one of the sights they go to see is an old house called Banshee Towers, which is holding an exhibition of sea paintings. As the name suggests, Banshee Towers has a reputation for being haunted, visitors are being scared away by ghostly wails, and paintings are disappearing from the exhibit.