The largest school on Earth is a ship. Someone aboard is trying to sink it.
Fifteen-year-old Mari Vega notices things. It's the only talent that ever got her anywhere, and it just won her a scholarship aboard the MV Giant of the Seas, a retired mega cruise liner reborn as a school that circles the globe and takes on new students at every port. Eight hundred kids from seventy countries. Classrooms that used to be casinos. Below the waterline, whole decks have been sealed since the refit, and the old ship is still down there waiting under the new paint.
The trouble starts small. A false alarm stops the ship cold in the middle of the Atlantic. A month of food spoils overnight. Grades get hacked, letters get forged, and rats turn up the day before a health inspection. It all looks like bad luck until Mari starts pulling threads with Theo Beckett, who grew up aboard, and Junie Park, who knows everyone worth knowing. The same hand is behind every incident. Someone on the faculty is not who they claim to be. The school is one failed review away from losing its charter, the ship is one bad year from the scrapyard, and the accidents are starting to look like a plan.
To catch a saboteur, the three of them form a secret society named for the deck the Giant never had. But every small mystery they solve uncovers a piece of the big one nobody will talk about: what really happened aboard this ship twenty years ago, and why someone would cross an ocean to keep it buried.
A whodunit where every clue is in plain sight, for readers of Truly Devious and Greenglass House.