On the Dionysia, the most private cruise ship at sea, there are only three rules.

Every guest disembarks alive. Every companion is of age. Every pleasure is consented to.

Beyond those three rules, whatever happens aboard stays aboard, and Madalena Santos, the Concierge, has spent seven years making sure it does.

She is excellent at her job. She has to be.

Then billionaire Clarence Buford charters the entire ship for his seventieth birthday and fills the guest list with the family who can't wait to inherit from him.

By the time the old man turns up dead, Madalena has a killer among her guests and a boat full of suspects who all have reasons and alibis.

But murder isn't the only problem.

Nine teenagers boarded with the Buford party. Madalena talked herself out of the one instinct that has never once lied to her. Now those children are gone, and she is beginning to understand what her ship was really chartered to carry.

The waters are closing in. The passengers are lying. And the darkest secret aboard the Dionysia is the one Madalena has been keeping since she was twelve years old.

Whatever happens on the ship stays on the ship.

She's counting on it.