This is a time travel book. David is a doctor in the future, Lisette is a rich man's daughter in Memphis over a hundred years before. There's a portal on the top level of a boat, and another in the fountain at the Peabody hotel.
David falls for Lisette, but when he looks up her fate in the future, she disappears on a ship in an event that was a historical mystery... and *his* name is on the passenger list, as well.
It was... long and predictable and I don't know if I wasn't in the mood for it or if it just didn't suck me in the way I wanted it to, but it... was a slog. I can't tell you why. There were extensive characters, there was good dialogue, there was plot and characterization and good writing... I just felt... nothing. And... I wanted to. So...