Terra Cotta Warriors have been discovered on other planets in the Milky Way Galaxy. And Lyra Daniels' parents are the archaeological Experts (yes with a capital E) on the Warriors and have dragged her to the various planets to study them despite the time dilation causing havoc with her social life. When one of the many Warrior planets goes silent, and looters attack her research base, Lyra becomes involved in discovering why the Warriors were placed on these planets. And, more importantly, by who.