Series numeration from Fantastic Fiction.

Kit Brightling, rescued as a foundling and raised in a home for talented girls, has worked hard to rise through the ranks of the Isles' Crown Command and become one of the few female captains in Queen Charlotte's fleet. Her ship is small, but she's fast--in part because of Kit's magical affinity to the sea. But the waters become perilous when the queen sends Kit on a special mission with a partner she never asked for. Rian Grant, Viscount Queenscliffe, may be a veteran of the Continental war, but Kit doesn't know him or his motives--and she's dealt with one too many members of the Beau Monde. But Kit has her orders, and the queen has commanded they journey to a dangerous pirate quay and rescue a spy who's been gathering intelligence on the exiled emperor of Gallia. Kit can lead her ship and clever crew on her own, but with the fate of queen and country at stake, Kit and Rian must learn to trust each other, or else the Isles will fall.... -- from back cover.