An unputdownable historical mystery series from bestselling author Holly Webb. 'A rollicking, fun read ... Rich with historical texture that brings the past vividly to life, Holly once again proves why she's a true superstar of children's fiction.' Hannah Gold, author of The Last Bear 'A gripping, believable 9+ historical mystery, full of courage, high stakes and quick wits.' Guardian Did you know that the Girl Guides worked undercover for MI5 during the First World War? When Phyl is dragged along to the Girl Guides by her younger sister, Annie, the last thing she expects is the adventure of a lifetime. Then her Guide captain offers her a job as a messenger for MI5. Phyl is desperate to help the war effort and is thrilled to be working with spies. But she can't seem to do anything right in the eyes of the grumpy Major Warren. When he suddenly disappears, Phyl and Annie suspect that he may in fact be a double agent. The two sisters must solve the mystery of his whereabouts, before it's too late. Luckily their friends from the Rose Patrol are ready to help... Perfect for fans of Robin Steven's Murder Most Unladylike series, Fleur Hitchcock and Katherine Woodfine.