Historical -- Assassin - girl in cell

This is the book that came to mind, but I’m like you with it being years since I read it. So, I don’t know. See if the blurb sounds familiar. The heroine is blind or at least blind for most of the book, if I’m recalling correctly.

Hope somebody has the answer if this isn’t it.

The Spymaster’s Lady by Joanna Bourne (1/08) (A Subtle+) [1-24-08]

France and England,1802

SHE'S NEVER MET A MAN SHE COULDN'T DECEIVE...
She's braved battlefields. She's stolen dispatches from under the noses of heads of state. She's played the worldly courtesan, the naive virgin, the refined British lady, even a Gypsy boy. But Annique Villiers, the elusive spy known as the Fox Cub, has finally met the one man she can't outwit...

UNTIL NOW.
British spymaster Robert Grey must enter France and bring back the brilliant, beautiful--and dangerous--Fox Cub. His duty is to capture her and her secrets for England. When the two natural enemies are thrown into prison, they forge an uneasy alliance to break free. But their pact is temporary and betrayal seems inevitable. They flee, pursued every step of the way by ruthless authorities, caught in a net of secrets and lies. As the fates of nations hang in the balance, Grey and Annique fight the passion that flares between them--forbidden, impossible, and completely irresistible...

—Janie

Could it be A Lady's Revenge by Tracey Devlyn