Unlocked

Unlocked is a companion instalment of the Keeper of the Lost Cities series by Shannon Messenger, published in 2020. It is numbered 8.5 in the sequence and is described as picking up directly from the cliffhanger that closes the previous book.

Its chapters alternate between two viewpoints, Sophie's and Keefe's, which gives the book a shape the main novels do not have and lets the reader follow both characters through the same stretch of story. The material it covers follows on from the ending of Legacy rather than starting somewhere new.

Alongside the narrative the volume carries a complete guide to the series, illustrated in colour and in black and white, and the other extras that belong with it. The book is therefore part story and part reference, and it is aimed at readers who have followed the series that far. It is not a place to begin, since everything in it assumes the earlier books.

The extras are the reason the volume exists as a separate book, and the guide is presented as a companion to the main sequence rather than as a continuation of it. Readers are expected to arrive already knowing what has happened so far.