During her high school graduation trip, Romy and dozens of other young people find themselves trapped aboard a luxurious cruise ship governed by deadly rules. Her only chance of survival is to raise the affection level of Silas, the ship's mysterious and monstrous first mate, to 100 and claim the reward.
At first, Romy is forced to get close to Silas simply to stay alive. But as she learns to manipulate the rules and save other passengers, she gradually falls in love with the very monster who is supposed to be incapable of human emotion.
Together, Romy and Silas survive a deadly masquerade ball, a sinking ship trial, and the secrets hidden within the ship's maritime archives. In the end, Romy tears her own name from the missing passengers' list and escapes back to the real world—only to encounter Silas once again aboard the real Ocean Crown.
