When a discovery that might be the key to deciphering the mysterious script of the Indus Valley Civilisation proves to be a puzzle in three languages, it’s a job for Codex, who’s a linguist, mathematician and all-round geek. But Codex soon discovers that this isn’t like anything she’s done before. As the sinister implications of the find become apparent, Codex must work with Agent Lila Raman to get to the bottom of a four-thousand-year-old mystery.