An illustrated, in-world companion to The Trials of Apollo and the wider Camp Half-Blood universe, framed entirely as the secret journal of Claudia, the newest recruit at Camp Jupiter. A probatio in the Fourth Cohort of the Twelfth Legion and a legacy of Mercury, the god of thieves and tricksters, Claudia has barely settled in when a string of sinister incidents begins wreaking havoc across the Roman demigod camp, threatening to tear the legion apart. Because the trouble started right after she stumbled into camp, and because of her larcenous divine ancestry, suspicion falls squarely on her. To clear her name, Claudia turns detective, recording her investigation in journal entries as she visits the crime scenes scattered around camp, from a row of seats in the arena to an underground aqueduct tunnel and the strange staircase behind the principia. Her digging uncovers a secret so ancient that not even the lares, the camp's resident ghosts, remember it, a hidden danger that could mean the end of Camp Jupiter itself. Along the way she befriends fellow newcomers and observes established heroes such as praetors Reyna and Frank Zhang through the fresh, often funny eyes of an outsider trying to belong. Set in the aftermath of Gaea's defeat during the Trials of Apollo era and illustrated by Stefanie Masciandaro and John S. Dykes, this short, breezy companion spotlights Roman camp life and the experience of finding your place among heroes.