Can you please suggest me either a book or a book series where children are protagonists and are searching for some kind of promised land?

A book or a series where children are persecuted in the world they live in (e.g. working as slaves) and hear about some safe refuge or shelter where they can be happy and secure. Books where there is a plot twist e.g. the promised land is an invented lie, the promised land is a false utopia and is actually oppressive as well and the promised land was destroyed or is actually a trap by the enemies are also OK as well.