There is no Deck 13. Officially.
Mari Vega is famous now, and she hates it. Last year she exposed a saboteur aboard the MV Giant of the Seas and kept the floating school from being shut down. This year the ship faces something quieter and far more dangerous: a charter review, run entirely on paperwork, that could hand the school to people who never wanted it to exist.
The trouble starts with a document that is perfect in every way except one. It is dated wrong. Then another surfaces, and another, each one flawless, each one impossible, and each pointing the blame at someone who cannot defend themselves on paper.
To save the ship a second time, Mari and the Deck Thirteen Society will have to prove that the cleanest records aboard are the forged ones, and that the truth has been hiding all along in a library, a laundry, and a column of chalk nobody was ever meant to read.
Verify twice. Protect the innocent first. Nobody investigates alone.
The ship is a member.