Keeper of the Lost Cities Series Books in Order

The Keeper of the Lost Cities Series is an expansive middle-grade and young adult fantasy series written by Shannon Messenger. The series follows Sophie Foster, a twelve-year-old girl who has always felt out of place among humans — she can read minds, which makes ordinary school and social life a constant ordeal. Her world is transformed when she discovers that she is actually an Elf, a member of a secret, technologically advanced civilisation that has hidden itself from humans for millennia. Relocated to the Lost Cities (the hidden elven world), Sophie discovers extraordinary abilities, dangerous enemies, and the beginnings of a vast conspiracy that threatens both elven and human civilisation.

Messenger's world-building is extraordinarily detailed — the elven society with its ability-based social structure, its extinct species and political factions, its complex relationships with other intelligent beings (gnomes, dwarves, goblins, ogres, trolls), and its millennia of hidden history is one of the most fully realised fantasy worlds in middle-grade fiction. The series manages to keep expanding its scope and raising its stakes across a very long run without losing narrative coherence, which is a significant achievement.

Comprising 9 main novels published from 2012 through 2024 (with additional companion novellas and short story collections), the series has become a phenomenon in middle-grade fantasy comparable to Percy Jackson in its world-building ambition and reader devotion. Ideal for readers aged 10–16 who are ready for long, complex fantasy with a strong female protagonist. Must be read strictly in order from Keeper of the Lost Cities (Book 1) — the overarching plot is continuous across the full series.