It has been suggested that the book was influenced by L. T. Meade's 1892 book Four on an Island, which also recounts a story of four related children including a tomboy along with a dog living on an island with a shipwreck.
Plot
When siblings Julian, Dick and Anne cannot go for their usual summer holiday to Polseath, they are invited to spend the summer with their Aunt Fanny and Uncle Quentin at their home Kirrin Cottage, in the coastal village of Kirrin. They also meet their cousin Georgina, a surly, difficult girl, who tries hard to livelike a boy and only answers to the name George. Despite an uncomfortable start, the cousins become firm friends and George introduces them to her beloved dog Timothy, who secretly lives with a fisher boy in the village as George's parents will not allow her to keep Timmy. On their way to Kirrin Island, George shows her cousins a shipwreck, explaining it was her great-great-great grandfather's ship. He had been transporting gold when the ship was wrecked in a storm, but despite divers investigating the wreck, the gold was never found. After visiting the wreck, the five arrive on the Island and are exploring the ruined castle when a huge storm blows up, making it too dangerous for them to return to the mainland. While they take shelter on the island, the sea throws up the old shipwreck, grounding it on the rocks surrounding the island. Excited by these developments, they decide to come back at dawn the next day to investigate the wreck before it is discovered. The following day, the five visit the wreck and discover the captain's cabin, where they find some objects belonging to George's great-great-great grandfather, including an old box which they take back to Kirrin Cottage. The box proves difficult to open, so they throw it from the highest window of the house. The box breaks open, but the noise disturbs Uncle Quentin who confiscates the box. Not willing to give up their quest, Julian sneaks into Uncle Quentin's study and takes the box, which contains an old map of Kirrin Castle. The children realise it is a treasure map showing the location of the lost gold. After making a tracing of the map and returning the box, they decide to find the gold themselves. To the children's shock, the box containing the map is sold to an antique collector. The same man also makes an offer to buy Kirrin Island. The children realise he has unearthed the secret map and wants the gold for himself, and so begins a race for the five to get to the gold first. Thinking the children want to spend time at the island before it is sold, Uncle Quentin and Aunt Fanny allow them to go camping there. Arriving on the island, the five start searching the castle ruins to locate the old dungeons where the gold is hidden. Chasing a rabbit, Timmy falls down an old well, from where the children find the dungeon entrance. Exploring underground, they find the gold in a locked vault. Trouble soon arrives, as bad men come to the island hoping to steal the gold. They capture George and Julian, locking them in the dungeons. Unable to find Anne and Dick, they leave the island, taking the oars from the children's boat so they cannot escape. Anne and Dick use the well shaft to rescue Julian and George from the dungeon, and the children hatch a plan to trap the men when they come back to the island with a boat to steal the gold. Although the plan goes wrong, they manage to leave the men stranded on Kirrin Island. They return to the mainland to tell Uncle Quentin, Aunt Fanny and the police what has happened. The gold is recovered and it is decided that it legally belongs to George's family, making them rich and enabling them to afford everything they have ever wanted. George's only wish is to be allowed to keep Timmy, and her parents agree. George also agrees to go toboarding school with Anne, because she and her cousins have become very good friends.
Film adaptations
An 8-part Children's Film Foundationfilm serial was produced in 1957, directed by Gerald Landau. In early 2010, rumours appeared that there might be a Five on a Treasure Island film to be released in 2012. On 31 May those rumours were confirmed by film makerSam Mendes on an interview about the upcoming Skyfall. Mendes stated, "A script is under way and is hoped to be in cinemas Spring 2012." Progress on the film was stopped when MGM went bankrupt later in the year.
Miscellaneous
In 1992, Fabbri published Five on a Treasure Island as No.50.