Story in the form of an all-ages mystery themed graphic novel that plays on the theme of a conspiracy, with an emphasis on showing through illustration rather than telling through dialog.
A group of children on a colony on a distant planet have built a secret clubhouse in an old service tunnel that they found near the landing site of their original colony ship. It's in an area that they're forbidden to go because it's supposedly dangerous.
The children are exploring and they find some of the machines used to construct the colony. In one of them there is an old toolbox containing the picture of a family that none of them recognize. The family is from a minority background, with a distinct name (written on the back of the picture). So everyone is certain that would have heard of them (Nobody knows what Korea is as there are no Koreans on the colony, and the language is unknown to the characters).
They explore further and find an old rest area filled with lockers. The lockers contain more personal effects from people that nobody has ever heard of.
The children search the colony's archives and find that there are inconsistencies when they compare the computer records to old paper journals and log books in the museum. Dates don't match up, people are mentioned in relation to events that happened before they were born, or years after they died. And the number of colonists doesn't match the apparent birth rate. There should be a lot more people than there actually are.
The children conclude that an event that nobody wants to talk about when the colony was first established was actually some kind of terrible accident that was covered up. Hundreds of people must have died. And that the council of the time faked the records so that Earth wouldn't find out and replace them.
The twist at the end is that the colony isn't a young colony set up by their grandparents in readiness for settlers from Earth, it's actually fully established and is hundreds of years old. The new settlers from Earth that they're waiting for actually arrived hundreds of years ago, and are ancestors.
Every coupe of generations the council have been sending colonists out to found new colonies all over the planet in order to keep the numbers down, and to prevent people from collecting too many records, and that rather than being a few hundred humans on the planet there are about a million people in dozens of colonies, each thinking that that their colony and the main one were the only two outposts.
The question is why would the council do this?
I'm looking for something that doesn't involve aliens or time travel, or some kind of disaster having happened (The twist is that there was no disaster to be covered up).
Earth is perfectly OK, and the final scene is revealing that rather than this being our near future and the issues being discussed being about our time, it's actually very very far in the future, and they're discussing things that are are a running theme throughout human history.