The Secret by Enid Blyton Books in Order

The Secret series follows Peggy, her younger twin siblings Mike and Nora, and their friend Jack through adventures that begin close to home and later take them much farther away. Enid Blyton introduced them in The Secret Island in 1938, before several of her other adventure series. Their stories combine the practical pleasures of making a home, finding food and exploring outdoors with mysteries that demand courage and cooperation. The children want freedom and safety, but their curiosity repeatedly brings them into contact with adults who have something to hide.

The first book gives that desire for independence a clear setting. Believing their parents lost, Peggy, Mike and Nora live with harsh relatives, while Jack has troubles of his own. Together they escape to a deserted island in a lake. They build a shelter from willow branches and bring animals across to provide milk and eggs. The island offers space to create their own small household, although staying hidden means watching for visitors and taking care whenever someone goes ashore.

The friendship formed on the island carries the children through the later books, even as the scale of their adventures grows.

In The Secret of Spiggy Holes, caves and passages near an old house lead them into a kidnapping mystery. Prince Paul becomes part of their circle, connecting their everyday lives to the kingdom of Baronia. The Secret Mountain takes the group to Africa to search for Captain and Mrs Arnold, whose disappearance makes the adventure personal. The children face unfamiliar country and need help from someone who knows it, giving their usual resourcefulness a much harder test.

A holiday in Baronia provides the setting for The Secret of Killimooin, also published as The Secret Forest. Mountain paths, a remote castle and a forest enclosed by steep slopes make exploration difficult. Rumors, robbers and the terrain itself add danger. In The Secret of Moon Castle, an isolated holiday house presents a different puzzle: instruments sound without players, objects move unexpectedly, and the children suspect that the strange events conceal a human explanation. Both stories turn places that promise an enjoyable holiday into settings where the friends must pay attention and investigate.

These are children’s adventure stories with outdoor exploration, hidden routes and suspense at their center. Reading from The Secret Island introduces the friendships before the later journeys expand their world. Blyton wrote five books in the series, with The Secret of Moon Castle appearing in 1953. A later continuation, The Secret Valley, was written by Trevor J. Bolton and published in 2009.