“People just call me Finn,” he says, by way of introduction.

Finn is retired after a 20-odd-year career with an unnamed government agency, but he still handles a contract job for them once in a while. The series begins in Puerto Rico with Assassins and Liars, when Finn meets Mary. He’s leaving on a mission when she asks to hitch a ride on his sailboat. Mary doesn’t care where he’s going; she’s desperate to leave Puerto Rico. Finn takes her along, thinking she’ll provide cover for his clandestine mission. The trouble begins before they even leave port.

Mary has more baggage than just the backpack she takes aboard Finn’s boat, Island Girl. Her explanation for a violent attack by three thugs before their departure is only the first of many tales she spins. The way she handles herself impresses Finn, but the story she tells about how she learned to fight gives him pause. He begins to wonder who she really is and why she’s there. Is her presence in his life mere chance?

Like Scheherazade in One Thousand and One Nights, Mary is a charmer. Over the course of the series, she keeps Finn guessing. She’s still a puzzle, even when they become partners working for a clandestine organization that deals with crimes the government chooses to ignore.

Although he can’t solve the mystery that’s Mary, Finn eventually comes to trust her, at least as much as he trusts anyone. Together, Finn and Mary are a formidable team, but how long will their partnership last?