The Cipher - Francis Diana Pharaoh

Lucy Trenton's ability to sense majick is one of her most dangerous secrets. But only one.

A blackmailer knows the other.

Suddenly, Lucy is caught in a treasonous plot to destroy the crown, and she's trapped in the tentacles of a desperate, destructive majick. Her only hope is ship captain Marten Thorpe, who-by every account-cannot be trusted. With time running out, Lucy must find a way to win a dangerous game or lose everything she holds dear.